We thank Kymberlee O&#39;Brien, Celia Moore, and Edward Tronick (Department of Psychology, University of Massachusetts,&#160;Boston) for providing the human hair samples analyzed in this study, and Stephen Suomi and Amanda Dettmer (Laboratory of Comparative Ethology, NICHD) for providing the rhesus monkey hair samples. Initial development and continued use of this method has been supported by NIH RR11122 to M.A.N.

1. Sample Collection and Storage
<ol>
	<li>Human hair
	<ol>
		<li>Secure the entire length of the hair to be sampled (up to a pencil-width in diameter) with a rubber band or clip. Cut hair as close to the scalp as possible (taking care not to nick the skin) with a clean scissors. Note: The standard sampling area is the posterior vertex of the skull.</li>
		<li>Some investigators have reported a decline in human hair CORT levels&#160; with distance from the scalp6, which may be due to washout from repeated exposure to water and shampoo7 (though see Manenschijn et al.8 and Thomson et al.9 for contrary results in which no segmental decline was observed) To minimize the impact of this potential &#34;washout effect&#34;, we recommend collecting hair segments proximal to the scalp with a length no greater than 3 cm (assuming an average growth rate of 1 cm/month10, a 3&#160;cm segment contains CORT that has been deposited over approximately the last 3 months). To accomplish this, use a ruler to measure 3 cm from the first cut and cut again to yield the 3&#160;cm sample. Note: Once the hair has been cut to length, it is no longer necessary to keep the strands in alignment unless the study involves cutting the sample into separate 1&#160;cm&#160;long segments to establish a retrospective calendar of CORT deposition over the time period prior to sampling6.</li>
		<li>Place the hair sample in a pouch made of aluminum foil, a clean paper envelope, or a 15&#160;ml screw-cap polypropylene centrifuge tube of the type used for sample washing. As CORT is extremely stable in hair2, samples can be stored indefinitely at -20 &#176;C and, if necessary, shipped overnight at ambient temperature.</li>
		<li>The hair collection procedure should be practiced on volunteers and the practice samples should be weighed before embarking on a full study. Note: Hair samples as small as 5-10 mg can be analyzed using the methods described here, although it is desirable to collect samples &#62;10 mg to minimize the likelihood of obtaining EIA readings below the lowest CORT standard.</li>
	</ol>
	</li>
	<li>Monkey hair
	<ol>
		<li>Shave hair (100-250 mg) from the nape of the neck using a standard animal clipper. Shave as close to the skin as possible, being careful not to nick the skin and cause bleeding because blood CORT levels are extremely high compared to those found in hair. Note: The neck area was chosen for routine sampling because it is generally a good source of hair and can be readily observed for hair regrowth prior to resampling.</li>
		<li>Place the hair sample in a pouch made of aluminum foil or a 15&#160;ml screw-cap polypropylene centrifuge tube. Monkey hair samples should be stored and shipped in the same manner as described above for human hair samples.</li>
		<li>Because monkey hair, unlike human scalp hair, grows to a certain length and then stops growing11, it is generally not feasible in this case to use distance from the skin as a calendar for CORT deposition. However, if an animal can be sampled more than once (for example, during periodic routine health exams), it is desirable to perform an initial shaving to set a baseline time point and then reshave the same area after the desired time period has elapsed. CORT in the second sample was deposited during the shave-reshave interval, which permits a precise attribution of the sample&#39;s CORT content to HPA activity over that interval5.</li>
	</ol>
	</li>
</ol>
2. Sample Washing and Drying
<ol>
	<li>Washing
	<ol>
		<li>Place each hair sample into a 15&#160;ml screw-cap polypropylene centrifuge tube.</li>
		<li>Add 5 ml of high&#160;performance liquid chromatography (HPLC)-grade isopropanol to each tube followed by repeated inversion for 3 min using a rotator.</li>
		<li>Decant the isopropanol into a waste container, taking care not to lose any of the sample.</li>
		<li>Repeat steps 2.1.2 and 2.1.3 once more.</li>
	</ol>
	</li>
	<li>Drying
	<ol>
		<li>Dry the hair for at least 2-3 days to ensure complete isopropanol evaporation.</li>
	</ol>
	</li>
</ol>
3. Sample Grinding and CORT Extraction - Method 1 for Large Samples
<ol>
	<li>Sample grinding
	<ol>
		<li>Place up to 250 mg of dried hair into a 10&#160;ml stainless steel grinding jar along with a single 12&#160;mm stainless steel grinding ball.</li>
		<li>Grind the sample for 6 min at a speed of 25 Hz using a ball mill.</li>
		<li>Weigh up to 50 mg of powdered hair on an analytical balance and then transfer it to a clean 2.0&#160;ml polypropylene microcentrifuge tube for subsequent CORT extraction.</li>
	</ol>
	</li>
	<li>CORT extraction
	<ol>
		<li>Add 1.0 ml of HPLC-grade methanol to the microcentrifuge tube containing the powdered sample.</li>
		<li>Cap the tube and incubate the sample for 18-24 hr at room temperature with constant inversion using a rotator.</li>
		<li>Centrifuge the tubes at 14,000 rpm&#160;for 1 min at room temperature to pellet the powdered hair.</li>
		<li>Transfer 0.6 ml of the supernatant to a clean 1.5&#160;ml microcentrifuge tube, taking care not to disturb the pellet of powdered hair.</li>
	</ol>
	</li>
</ol>
4. Sample Grinding and CORT Extraction - Method 2 for Small Samples
<ol>
	<li>Sample grinding
	<ol>
		<li>Place up to 60 mg of hair into a preweighed 2&#160;ml microcentrifuge tube reinforced for bead beating.</li>
		<li>Reweigh the vial to obtain the sample weight.</li>
		<li>Add three 3.2&#160;mm chrome steel beads to each vial and then grind the sample for at least 2 min in a bead beater. If visual inspection reveals that the sample is insufficiently pulverized, then perform additional grinding for 0.5 or 1 min. Note: No transfer of the ground hair is needed in this case because CORT extraction is performed in the same vial as grinding.</li>
	</ol>
	</li>
	<li>CORT extraction
	<ol>
		<li>Add 1.5 ml of HPLC-grade methanol to the microcentrifuge tube containing the powdered sample.</li>
		<li>Cap the tube and incubate the sample for 18-24 hr at room temperature with constant inversion using a rotator.</li>
		<li>Centrifuge the tubes at 10,000 rpm for 5 min at room temperature to pellet the powdered hair. Note: The chrome steel beads remain in the tube with the hair during the extraction and centrifugation steps, which accounts for the lower centrifugation speed compared to method 1.</li>
		<li>Transfer 1.0 ml of the supernatant to a clean 1.5&#160;ml microcentrifuge tube, taking care not to disturb the pellet of powdered hair.</li>
	</ol>
	</li>
</ol>
5. Solvent Evaporation and Sample Reconstitution
<ol>
	<li>Dry down the methanol using either a vacuum evaporator or a stream of nitrogen gas if a vacuum evaporator is not available. If a vacuum evaporator is used, the methanol vapor can be trapped by means of a cold trap or a chemical trap equipped with an activated charcoal cartridge.</li>
	<li>Following removal of the methanol, reconstitute the CORT extract in an appropriate volume of EIA assay buffer (assay diluent). If relatively high CORT values are anticipated, then use a buffer volume of 0.4 ml or greater. If relatively low values are anticipated, then the volume can be reduced to 0.2 ml or less to increase sensitivity. Note: 0.2 ml is sufficient volume to run duplicate aliquots of the sample at least twice in case a rerun of the sample is required.</li>
	<li>Either assay the reconstituted sample immediately or freeze it at -20 &#176;C for later analysis. Note: If the reconstituted sample is frozen, it is important to avoid sublimation during the freezing period since an alteration in sample volume will lead to a false CORT value when the final calculations are performed.</li>
</ol>
6. CORT Assay and Data Conversion
<ol>
	<li>Assay the hair extracts for CORT using a high-sensitivity enzyme immunoassay (EIA) kit. Note: If using a commercial salivary CORT EIA kit, follow the manufacturer&#39;s recommendations as specified in the kit insert except that the test samples will be duplicate aliquots of each reconstituted hair extract instead of saliva samples.</li>
	<li>Prepare a quality-control (QC) hair extract for use in every assay.
	<ol>
		<li>Collect a number of extra hair samples and either process them individually as in steps 4.1 and 4.2 or pool them for large sample processing as in steps 3.1 and 3.2.</li>
		<li>Evaporate the solvent and reconstitute the extracts as in steps 5.1 and 5.2, then pool the reconstituted extracts from several individual or pooled samples.</li>
		<li>Aliquot an appropriate volume of the pooled reconstituted extract (e.g.&#160;0.10 ml) into individual microcentrifuge tubes and freeze for later use.</li>
		<li>Thaw and run one QC aliquot in duplicate on each immunoassay microplate to provide a reference CORT value for checking the quality of each run.</li>
		<li>An intra-assay coefficient of variation (CV; defined as the standard deviation divided by the mean of a set of sample values) can be calculated by analyzing 10-12 QC wells in the same run, whereas an inter-assay CV can be calculated using the QC values across a group of runs. If one&#39;s microplate reader software calculates a CV for the duplicate wells representing each hair extract, then an alternate method for determining intra-assay CV is to calculate the mean of those individual CV values across the entire plate.</li>
		<li>If any sample extract yields a reading greater than the highest CORT standard in the EIA, then another aliquot of the extract is diluted with an appropriate amount of assay buffer and the subsequent EIA reading is corrected for the dilution factor. Samples are also routinely reanalyzed if the CV for the duplicate wells is &#62;10%.</li>
		<li>Because CORT EIA kits are designed to measure CORT values in liquid samples such as saliva or plasma, the output of the microplate reader software must be converted to amount of CORT per unit weight of powdered hair. The following formula converts assay output in &#956;g/dl to pg CORT per mg hair: 
		(A/B) * (C/D) * E * 10,000 = F 
		where A = &#956;g/dl from assay output; B = weight (in mg) of hair subjected to extraction; C = vol. (in ml) of methanol added to the powdered hair; D = vol. (in ml) of methanol recovered from the extract and subsequently dried down; E = vol. (in ml) of assay buffer used to reconstitute the dried extract; and F = final value of hair CORT concentration in pg/mg.</li>
	</ol>
	</li>
</ol>

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	<li>Selye, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stress+and+the+general+adaptation+syndrome.">Stress and the general adaptation syndrome.</a> Br. Med. J. 1 (4667), 1383-1392 (1950).</li><li>Meyer, J. S., Novak, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minireview:+Hair+cortisol:+A+novel+biomarker+of+hypothalamic-+pituitary-adrenocortical+activity.">Minireview: Hair cortisol: A novel biomarker of hypothalamic- pituitary-adrenocortical activity.</a> Endocrinology. 153, 4120-4127 (2012).</li><li>Tiefenbacher, S., Novak, M. A., Lutz, C. K., Meyer, J. 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+physiology+and+neurochemistry+of+self-injurious+behavior:+A+nonhuman+primate+model.">The physiology and neurochemistry of self-injurious behavior: A nonhuman primate model.</a> Front. Biosci. 10, 1-11 (2005).</li><li>Davenport, M. D., Tiefenbacher, S., Lutz, C. K., Novak, M. A., Meyer, J. S. <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+endogenous+cortisol+concentrations+in+the+hair+of+rhesus+macaques.">Analysis of endogenous cortisol concentrations in the hair of rhesus macaques.</a> Gen. Comp. Endocrinol. 147, 255-261 (2006).</li><li>Davenport, M. D., Lutz, C. K., Tiefenbacher, S., Novak, M. A., Meyer, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rhesus+monkey+model+of+self+injury:+Effects+of+relocation+stress+on+behavior+and+neuroendocrine+function.">A rhesus monkey model of self injury: Effects of relocation stress on behavior and neuroendocrine function.</a> Biol. Psychiatry. 63, 990-996 (2008).</li><li>Kirschbaum, C., Tietze, A., Skoluda, N., Dettenborn, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hair+as+a+retrospective+calendar+of+cortisol+production+-+Increased+cortisol+incorporation+into+hair+in+the+third+trimester+of+pregnancy.">Hair as a retrospective calendar of cortisol production - Increased cortisol incorporation into hair in the third trimester of pregnancy.</a> Psychoneuroendocrinology. 34, 32-37 (2009).</li><li>Hamel, A. F., Meyer, J. S., Henchey, E., Dettmer, A. M., Suomi, S. J., Novak, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+shampoo+and+water+washing+on+hair+cortisol+concentrations.">Effects of shampoo and water washing on hair cortisol concentrations.</a> Clin. Chim. Acta. 412, 382-385 (2011).</li><li>Manenschijn, L., Koper, J. W., Lamberts, S. W., van Rossum, E. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+a+method+to+measure+long+term+cortisol+levels.">Evaluation of a method to measure long term cortisol levels.</a> Steroids. 76, 1032-1036 (2011).</li><li>Thomson, S., Koren, G., Fraser, L. A., Rieder, M., Friedman, T. C., Van Uum, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hair+analysis+provides+a+historical+record+of+cortisol+levels+in+Cushing&#8217;s+syndrome.">Hair analysis provides a historical record of cortisol levels in Cushing&#8217;s syndrome.</a> Exp. Clin. Endocrinol. Diabetes. 118, 133-138 (2010).</li><li>LeBeau, M. A., Montgomery, M. A., Brewer, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+variations+in+growth+rate+and+sample+collection+on+interpreting+results+of+segmental+analyses+of+hair.">The role of variations in growth rate and sample collection on interpreting results of segmental analyses of hair.</a> Forensic Sci. Int. 210, 110-116 (2011).</li><li>Dolnick, E. H., Montagna, W., Dobson, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variability+of+hair+growth+in+Macaca+mulatta.">Variability of hair growth in Macaca mulatta.</a> Adv. Biol. Skin. IX, 121-128 (1969).</li><li>Sauv&#233;, B., Koren, G., Walsh, G., Uum Tokmakejian, S. V. a. n., H, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+cortisol+in+human+hair+as+a+biomarker+of+systemic+exposure.">Measurement of cortisol in human hair as a biomarker of systemic exposure.</a> Clin. Invest. Med. 30, 183-191 (2007).</li><li>Gow, R., Thomson, S., Rieder, M., Van Uum, S., Koren, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+assessment+of+cortisol+analysis+in+hair+and+its+clinical+applications.">An assessment of cortisol analysis in hair and its clinical applications.</a> Forensic Sci. Int. 196, 32-37 (2010).</li><li>Bechsh&#248;ft, T. &. #. 2. 1. 6. ;., Sonne, C., Dietz, R., Born, E. W., Novak, M. A., Henchey, E., Meyer, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortisol+levels+in+hair+of+East+Greenland+polar+bears.">Cortisol levels in hair of East Greenland polar bears.</a> Sci. Total Environ. 409, 831-834 (2011).</li><li>Cooper, G. A. A., Kronstrand, R., Kintz, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Society+of+Hair+Testing+guidelines+for+drug+testing+in+hair.">Society of Hair Testing guidelines for drug testing in hair.</a> Forensic Sci. Int. 218, 20-28 (2012).</li><li>Ito, N., Ito, T., Kromminga, A., Bettermann, A., Takigawa, M., Kees, F., Straub, R. H., Paus, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+hair+follicles+display+a+functional+equivalent+of+the+hypothalamic-pituitary-adrenal+(HPA)+axis+and+synthesize+cortisol.">Human hair follicles display a functional equivalent of the hypothalamic-pituitary-adrenal (HPA) axis and synthesize cortisol.</a> FASEB J. 19, 1332-1334 (2005).</li><li>Russell, E., Koren, G., Rieder, M., Van Uum, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hair+cortisol+as+a+biological+marker+of+chronic+stress:+Current+status,+future+directions+and+unanswered+questions.">Hair cortisol as a biological marker of chronic stress: Current status, future directions and unanswered questions.</a> Psychoneuroendocrinology. 37, 589-601 (2012).</li><li>Stalder, T., Kirschbaum, C. <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+cortisol+in+hair+-+State+of+the+art+and+future+directions.">Analysis of cortisol in hair - State of the art and future directions.</a> Brain Behav. Immun. 26, 1019-1029 (2012).</li><li>Staufenbiel, S. M., Penninx, B. W., Spijker, A. T., Elzinga, B. M., van Rossum, E. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hair+cortisol,+stress+exposure,+and+mental+health+in+humans:+A+systematic+review.">Hair cortisol, stress exposure, and mental health in humans: A systematic review.</a> Psychoneuroendocrinology. 38, 1220-1235 (2013).</li></ol>

The authors have no conflicts of interest to declare.

The hair CORT procedure described above is simple to perform, is relatively inexpensive, makes use of readily available chemicals, reagents, and supplies, and requires equipment that, with one exception, is likely to be present in a typical analytical laboratory. The exception is a grinding apparatus such as a ball mill or mini-beadbeater. We note that some research groups mince hair samples into small fragments roughly 1&#160;mm in length12, but based on our observations we recommend performing grinding instead of mincing if at all possible. Another area of methodological variation in the literature involves whether or not to wash the hair prior to CORT extraction13, and if so, what wash conditions to use. If washing is not performed, then one risks the possibility that the methanol extract will contain not only CORT incorporated slowly over the weeks or months of hair growth but also sweat- and/or sebum-derived CORT deposited recently on the surface of the hair. Studies on polar bear samples support the existence of two CORT fractions in hair: a loosely-bound fraction removable by brief isopropanol washing of intact hair that presumably represents mainly surface contamination, and a more tightly-bound fraction that is accessible by extensive methanol extraction of powdered hair samples14. The same conclusion can be drawn from the diminishing amounts of CORT extracted from monkey and human hair by repeated isopropanol washing (see Introduction). On the other hand, if washing is performed, then the choice of solvent and wash conditions can have a significant impact on the resulting CORT values. The Society of Hair Testing has published guidelines for selecting an appropriate solvent to minimize hair swelling and potential solute elution from the interior of the hair matrix during the washing process15. Although these recommendations were developed for application to drug testing in hair, they are relevant for steroid analysis as well.
Measuring CORT in hair rather than plasma or saliva offers a number of advantages2. Most importantly, this approach provides a biomarker of integrated CORT levels over periods of weeks to months that is uninfluenced by the time of day when samples are collected or by brief stress exposure prior to collection. Hair collection is noninvasive, although sampling of some animal species such as rhesus monkeys or bears may require anesthetization of the subject for safety reasons. Another advantage is that CORT is extremely stable in hair compared with other sample matrices, which permits analysis of historical or archival samples even if they have been stored at ambient temperature for a long period of time. Finally, CORT levels in human hair segments cut at successively greater distances from the scalp have sometimes been used to create a retrospective calendar of HPA activity over time. In such cases it is especially important to be aware of the previously mentioned &#8220;washout&#8221; effect produced by repeated hair washing. Although some studies have failed to replicate this effect8,9, it is worth noting that in those studies the samples were not washed prior to methanol extraction. This important methodological difference may help explain why hair CORT levels did not decline with distance from the scalp.
Some limitations of the hair CORT approach should also be mentioned. First, this approach cannot detect changes in the circadian rhythmicity of HPA activity (as seen in some depressed patients) or the awakening CORT response. Hair CORT levels also might not detect the impact of relatively brief stressors that occurred during the period of hormone incorporation. Hence, this approach should be thought of as complementary to measurements of salivary and/or plasma CORT, not as a replacement for such measurements. Second, whereas the use of hair CORT will likely be of particular value to researchers interested in psychosocial and environmental stressors, it is important to keep in mind that elevated HPA activity can occur under a variety of conditions, including physical exercise, metabolic abnormalities, and infectious disease. Third, whereas data exist from both humans and monkeys supporting the hypothesis that hair CORT is derived mainly from the bloodstream2, this hypothesis has not yet been proven. Indeed, Ito and coworkers16 have demonstrated the existence of a functional HPA-like system in microdissected human hair follicles maintained in organ culture. The degree to which hair follicles contribute to the CORT measured in the hair shaft remains unknown at this time.
In just a few years since its inception as a new biomarker of HPA axis activity, hair CORT has been used in a wide variety of applications across numerous species. Many of these applications fall within several major themes aimed at determining how long-term HPA activity is related to chronic stress, endocrine disorders such as Cushing&#8217;s disease, or neuropsychiatric disorders such as post-traumatic stress disorder2,17-19. Other studies have used hair CORT to examine HPA axis function in relation to behavioral temperament, normal development, the influence of developmental factors such as early childhood experiences in humans or different rearing conditions in monkeys, environmental conservation of wild-living animals, and retrospective investigation of historical or archival samples. Species studied to date with respect to hair CORT include humans, several species of nonhuman primates (macaques, vervet monkeys, and baboons), dogs, cats, cattle, horses, and several species of bears. It is likely that the use of hair CORT to assess long-term HPA activity, whether to investigate the physiological response to chronic stress or to address other experimental questions, will continue to expand and to be applied to an even greater range of species.

Measurement of CORT in plasma, saliva, or occasionally in urine or feces has been used as an index of physiological stress since Selye&#39;s discovery of the role of the HPA axis in stress1. Although numerous papers have been published relating HPA activity to acutely stressful situations, the field has been hampered by the lack of a simple and reliable index of chronic physiological stress. This problem arises because plasma and saliva both yield &#34;point&#34; estimates of HPA activity that are subject to circadian variation and can be confounded by environmental disturbances. Urinary and fecal samples yield measurements of CORT and/or metabolite excretion that span a number of hours up to a full day in some cases. Collection of multiple samples using any of these matrices may provide a rough composite index of CORT levels over time; however, none of these approaches provides a truly long-term index of HPA activity and the responsiveness of this system to chronic stressors.
Measuring CORT in hair has begun to fill this important need in the stress literature. Initial studies by several laboratories demonstrated the presence of CORT in human hair but did not investigate whether hair CORT levels changed as a function of stress2. As our laboratory has been interested for many years in the regulation of the rhesus monkey HPA axis by various social and behavioral factors3, we set out to establish and validate methods for extraction and analysis of rhesus monkey hair4. Based on the premise that blood-borne CORT is slowly and continuously incorporated into growing hair, the purpose of this new method was to use levels of hair-derived CORT as an integrated index of HPA activity over periods of weeks to months.
Several methodological challenges were encountered in developing the present protocol. First, previous studies had shown that small amounts of circulating CORT are excreted in sweat and sebum and therefore could coat the outside of the hair shaft2. In order to eliminate this potential confound, we developed a mild wash procedure that appears to remove external CORT while having a minimal effect on CORT present within the growing hair shaft. Thus, monkey hair subjected to this procedure (i.e.&#160;two 3-min washes with isopropanol) lost approximately 7-8% of the total hair CORT content, and a third wash removed less than 1% more steroid from the sample4. There appears to be more external CORT in human hair, since the same procedure removed an average of 27% total CORT content from the samples (K. Rosenberg and J. Meyer, unpublished). Like monkey hair, however, an additional wash contained much less CORT (about 7%) than the first two washes. Therefore, results from both monkey and human hair support the contention that most (if not all) external CORT can be removed while maintaining a major fraction of CORT within the internal hair matrix. Second, our pilot studies also showed that grinding the hair prior to extraction significantly increased CORT recovery from the sample, presumably by breaking open the complex proteinaceous matrix of the hair shaft as well as increasing the surface area available for solvent penetration. Two different grinding methods were developed, each with advantages and disadvantages. Method 1, which uses a ball mill, has the advantage of producing the finest powder. However, a ball mill is a relatively expensive equipment item and, if used with standard grinding jars and balls, it is capable of grinding only two samples at a time. Small samples are also difficult to process using a ball mill with standard grinding jars. Method 2, which uses a beadbeater, is less effective in its grinding ability. As a result, average CORT recovery is approximately 10% lower using this method compared to the ball mill (unpublished data). On the other hand, a beadbeater is considerably less expensive than a ball mill, 16-24 samples can be ground at once depending on the model, and the method is well suited for small samples. Because of the above mentioned differential recovery, it is advisable to use the same grinding method for all samples within a particular study.
Once the hair samples have been processed, they are extracted with methanol and CORT in the extracts is analyzed by means of a sensitive and specific commercial EIA kit originally designed to measure salivary CORT. The extraction and assay procedures were validated in part by demonstrating that serial dilutions of extracts from monkey hair samples yielded EIA readings that closely paralleled the readings obtained from authentic CORT standards. We then showed that hair CORT (in addition to plasma and salivary CORT) was sensitive to the major life stressor of an administratively mandated relocation of the monkeys to new housing quarters4,5. The present paper provides a detailed account of the methods used routinely in our laboratory to process human and monkey hair samples and to extract and analyze CORT from such samples.

<table border="0" cellpadding="0" cellspacing="0" width="798">
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		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">HPLC-grade isopropanol</td>
			<td style="width:116px;">Fisher</td>
			<td style="width:119px;">A451</td>
			<td style="width:247px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">HPLC-grade methanol</td>
			<td style="width:116px;">Fisher</td>
			<td style="width:119px;">A452</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">Salivary cortisol assay kits</td>
			<td style="width:116px;">Salimetrics</td>
			<td style="width:119px;">1-3002</td>
			<td>See manufacturer&#39;s kit insert for information on assay sensitivity and specificity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">15-ml polypropylene screw-cap centrifuge tubes</td>
			<td style="width:116px;">Max Scientific</td>
			<td>10-9151</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">1.5-ml Safe-Lock microcentrifuge tubes</td>
			<td style="width:116px;">Fisher</td>
			<td style="width:119px;">05-402-25</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">2.0-ml Safe-Lock microcentrifuge tubes</td>
			<td style="width:116px;">Fisher</td>
			<td style="width:119px;">05-402-7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2.0-ml XXTuff reinforced microvials</td>
			<td style="width:116px;">BioSpec</td>
			<td>330TX</td>
			<td>Use with mini-beadbeater</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3.2-mm chrome-steel beads</td>
			<td style="width:116px;">BioSpec</td>
			<td>11079132c</td>
			<td>Use with mini-beadbeater</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">10-ml stainless steel grinding jars</td>
			<td style="width:116px;">Retsch</td>
			<td style="width:119px;">02.462.0061</td>
			<td>Use with mixer mill</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">12-mm stainless steel grinding balls</td>
			<td style="width:116px;">Retsch</td>
			<td style="width:119px;">05.368.0037</td>
			<td>Use with mixer mill</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Savant activated carbon cartridge</td>
			<td style="width:116px;">Fisher</td>
			<td>DTK120R</td>
			<td>Use with Savant chemical trap</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;"></td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;"></td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">Name of Equipment</td>
			<td style="width:116px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">Rotator for 15-ml centrifuge tubes</td>
			<td style="width:116px;">Fisher</td>
			<td>S02135</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">Rotator for microcentrifuge tubes</td>
			<td style="width:116px;">Fisher</td>
			<td>NC9854190&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Benchtop centrifuge for microcentrifuge tubes</td>
			<td style="width:116px;">Fisher</td>
			<td>13-100-675</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">MM 200 mixer mill</td>
			<td style="width:116px;">Retsch</td>
			<td style="width:119px;">20.746.0001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mini-Beadbeater 16&#160;</td>
			<td style="width:116px;">BioSpec</td>
			<td>607</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Savant DNA Speedvac</td>
			<td style="width:116px;">Fisher</td>
			<td>DNA120-115</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Savant refrigerated vapor trap</td>
			<td style="width:116px;">Fisher</td>
			<td>RVT400-115</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Savant chemical trap</td>
			<td style="width:116px;">Fisher</td>
			<td>SCT120</td>
			<td>Alternative to refrigerated vapor trap</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microplate reader</td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microplate washer</td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microplate mixer</td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:316px;">Multichannel pipetter</td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Analytical balance</td>
			<td style="width:116px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

extraction and analysis of cortisol from human and monkey hair

The stress hormone cortisol (CORT) is slowly incorporated into the growing hair shaft of humans, nonhuman primates, and other mammals. We developed and validated a method for CORT extraction and analysis from rhesus monkey hair and subsequently adapted this method for use with human scalp hair. In contrast to CORT &#34;point samples&#34; obtained from plasma or saliva, hair CORT provides an integrated measure of hypothalamic-pituitary-adrenocortical (HPA) system activity, and thus physiological stress, during the period of hormone incorporation. Because human scalp hair grows at an average rate of 1 cm/month, CORT levels obtained from hair segments several cm in length can potentially serve as a biomarker of stress experienced over a number of months.
In our method, each hair sample is first washed twice in isopropanol to remove any CORT from the outside of the hair shaft that has been deposited from sweat or sebum. After drying, the sample is ground to a fine powder to break up the hair&#39;s protein matrix and increase the surface area for extraction. CORT from the interior of the hair shaft is extracted into methanol, the methanol is evaporated, and the extract is reconstituted in assay buffer. Extracted CORT, along with standards and quality controls, is then analyzed by means of a sensitive and specific commercially available enzyme immunoassay (EIA) kit. Readout from the EIA is converted to pg CORT per mg powdered hair weight. This method has been used in our laboratory to analyze hair CORT in humans, several species of macaque monkeys, marmosets, dogs, and polar bears. Many studies both from our lab and from other research groups have demonstrated the broad applicability of hair CORT for assessing chronic stress exposure in natural as well as laboratory settings.

Figure 1&#160;shows the printout from a representative set of human hair samples (adult male and female human subjects) processed using method 2 grinding and extraction. Computer software was used to generate the data output and to fit a 4-parameter sigmoidal curve to the CORT standards (Figure 2). The between-well CVs from this plate ranged from 0.01-5.73% with an average intra-assay CV of 1.34%. The inter-assay CV determined using the QC values from nine recent human hair assays was 4.41%.&#160;The 37 samples analyzed on this plate yielded a range of hair CORT values from 3.1-650 pg/mg (median = 10.2 pg/mg; mean&#177;SD = 36.0&#177;110 pg/mg).
Method 1 is used in our laboratory to process hair samples from nonhuman primates and other large animals. A representative assay of adult rhesus monkey hair (mostly from females) yielded a range of CORT values from 50.1-102 pg/mg (median = 75.0; mean&#177;SD = 75.8&#177;14.0 pg/mg). The average intra-assay CV for this assay was 2.08%, and the inter-assay CV determined using the QC values from nine recent monkey hair assays was 4.63%.
<img alt="Figure 1" fo:content-width="5in" fo:src="/files/ftp_upload/50882/50882fig1highres.jpg" src="/files/ftp_upload/50882/50882fig1.jpg" /> 
Figure 1. Software output for a representative human hair CORT assay. The duplicate wells are as follows: S1-S6 - CORT standards ranging from 0.012 &#956;g/dl (S6) to 3.0 &#956;g/dl (S1);&#160;S7 - 0 CORT wells; B1 - nonspecific binding (NSB) wells that lack anti-CORT antibody (the software automatically subtracts the average NSB optical density [OD] value from all other OD readings); C1 and C2 &#8212; high and low CORT calibrators provided by the manufacturer; T1 - QC; 
T2-T38 - test samples. From C1 to T38, the upper value in each cell of the array is the measured OD value from the corresponding well, and the lower value in the left-hand cell of the pair is the CORT value in &#956;g/dl calculated from the mean OD value. Note that samples T9 and T31 yielded readings above the highest CORT standard. As a result, both samples were later diluted 4-fold in assay diluent and reanalyzed. The reanalyzed values were used after correction for the dilution factor. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/50882/50882fig1highres.jpg" target="_blank">Click here to view larger image.</a>
<img alt="Figure 2" fo:content-width="5in" fo:src="/files/ftp_upload/50882/50882fig2highres.jpg" src="/files/ftp_upload/50882/50882fig2.jpg" /> 
Figure 2. Standard curve of OD values versus log CORT concentration for the same human hair assay. The R-squared value shown in panel A is the calculated goodness of fit of the curve to the standards. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/50882/50882fig2highres.jpg" target="_blank">Click here to view larger image.</a>

Watch this Scientific Journal Video about Extraction and Analysis of Cortisol from Human and Monkey Hair at JoVE.com

Extraction and Analysis of Cortisol from Human and Monkey Hair

Cortisol (CORT) accumulates in the growing hair shaft of humans and nonhuman primates. We describe methods for extracting and analyzing hair CORT with high precision and sensitivity. Measurement of hair CORT is particularly well-suited for assessing chronic stress over periods of weeks to months.

The stress hormone cortisol (CORT) is slowly incorporated into the growing hair shaft of humans, nonhuman primates, and other mammals. We developed and ...

extraction-and-analysis-of-cortisol-from-human-and-monkey-hair

Nanyang Technological University

Research

JoVE Journal

Biology

28.1K Views.  University of Massachusetts, Amherst. Cortisol (CORT) accumulates in the growing hair shaft of humans and nonhuman primates. We describe methods for extracting and analyzing hair CORT with high precision and sensitivity. Measurement of hair CORT is particularly well-suited for assessing chronic stress over periods of weeks to months.

Video: Extraction and Analysis of Cortisol from Human and Monkey Hair

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

Extraction of High Molecular Weight Genomic DNA from Soils and Sediments

The soil microbiome is a vast and relatively unexplored reservoir of genomic diversity and metabolic innovation that is intimately associated with nutrient and energy flow within terrestrial ecosystems. Cultivation-independent environmental genomic, also known as metagenomic, approaches promise unprecedented access to this genetic information with respect to pathway reconstruction and functional screening for high value therapeutic and biomass conversion processes. However, the soil microbiome still remains a challenge largely due to the difficulty in obtaining high molecular weight DNA of sufficient quality for large insert library production. Here we introduce a protocol for extracting high molecular weight, microbial community genomic DNA from soils and sediments. The quality of isolated genomic DNA is ideal for constructing large insert environmental genomic libraries for downstream sequencing and screening applications. 
The procedure starts with cell lysis. Cell walls and membranes of microbes are lysed by both mechanical (grinding) and chemical forces (&beta;-mercaptoethanol). Genomic DNA is then isolated using extraction buffer, chloroform-isoamyl alcohol and isopropyl alcohol. The buffers employed for the lysis and extraction steps include guanidine isothiocyanate and hexadecyltrimethylammonium bromide (CTAB) to preserve the integrity of the high molecular weight genomic DNA. Depending on your downstream application, the isolated genomic DNA can be further purified using cesium chloride (CsCl) gradient ultracentrifugation, which reduces impurities including humic acids. The first procedure, extraction, takes approximately 8 hours, excluding DNA quantification step. The CsCl gradient ultracentrifugation, is a two days process. During the entire procedure, genomic DNA should be treated gently to prevent shearing, avoid severe vortexing, and repetitive harsh pipetting.

A methodology to isolate high molecular weight and high quality genomic DNA from soil microbial community is described.

The soil microbiome is a vast and relatively unexplored reservoir of genomic diversity and metabolic innovation that is intimately associated with ...

DNA Extraction from Paraffin Embedded Material for Genetic and Epigenetic Analyses

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number gains and losses and DNA methylation. Advances in high-throughput, genome-wide profiling technologies, such as microarrays, have significantly improved our ability to identify and detect these specific alterations. However as technology continues to improve, a limiting factor remains sample quality and availability. Furthermore, follow-up clinical information and disease outcome are often collected years after the initial specimen collection. Specimens, typically formalin-fixed and paraffin embedded (FFPE), are stored in hospital archives for years to decades. DNA can be efficiently and effectively recovered from paraffin-embedded specimens if the appropriate method of extraction is applied. High quality DNA extracted from properly preserved and stored specimens can support quantitative assays for comparisons of normal and diseased tissues and generation of genetic and epigenetic signatures 1. To extract DNA from paraffin-embedded samples, tissue cores or microdissected tissue are subjected to xylene treatment, which dissolves the paraffin from the tissue, and then rehydrated using a series of ethanol washes. Proteins and harmful enzymes such as nucleases are subsequently digested by proteinase K. The addition of lysis buffer, which contains denaturing agents such as sodium dodecyl sulfate (SDS), facilitates digestion 2. Nucleic acids are purified from the tissue lysate using buffer-saturated phenol and high speed centrifugation which generates a biphasic solution. DNA and RNA remain in the upper aqueous phase, while proteins, lipids and polysaccharides are sequestered in the inter- and organic-phases respectively. Retention of the aqueous phase and repeated phenol extractions generates a clean sample. Following phenol extractions, RNase A is added to eliminate contaminating RNA. Additional phenol extractions following incubation with RNase A are used to remove any remaining enzyme. The addition of sodium acetate and isopropanol precipitates DNA, and high speed centrifugation is used to pellet the DNA and facilitate isopropanol removal. Excess salts carried over from precipitation can interfere with subsequent enzymatic assays, but can be removed from the DNA by washing with 70% ethanol, followed by centrifugation to re-pellet the DNA 3. DNA is re-suspended in distilled water or the buffer of choice, quantified and stored at -20&deg;C. Purified DNA can subsequently be used in downstream applications which include, but are not limited to, PCR, array comparative genomic hybridization 4 (array CGH), methylated DNA Immunoprecipitation (MeDIP) and sequencing, allowing for an integrative analysis of tissue/tumor samples.

This video demonstrates the protocol for DNA extraction from formalin-fixed paraffin-embedded material. This is a multi-day procedure in which tissue sections are deparaffinized with xylene, rehydrated with ethanol and treated with proteinase K to purify and isolate DNA for subsequent gene-specific or genome-wide analysis.

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number ...

A Noninvasive Hair Sampling Technique to Obtain High Quality DNA from Elusive Small Mammals

Noninvasive genetic sampling approaches are becoming increasingly important to study wildlife populations. A number of studies have reported using noninvasive sampling techniques to investigate population genetics and demography of wild populations1. This approach has proven to be especially useful when dealing with rare or elusive species2. While a number of these methods have been developed to sample hair, feces and other biological material from carnivores and medium-sized mammals, they have largely remained untested in elusive small mammals. In this video, we present a novel, inexpensive and noninvasive hair snare targeted at an elusive small mammal, the American pika (Ochotona princeps). We describe the general set-up of the hair snare, which consists of strips of packing tape arranged in a web-like fashion and placed along travelling routes in the pikas&#x2019; habitat. We illustrate the efficiency of the snare at collecting a large quantity of hair that can then be collected and brought back to the lab. We then demonstrate the use of the DNA IQ system (Promega) to isolate DNA and showcase the utility of this method to amplify commonly used molecular markers including nuclear microsatellites, amplified fragment length polymorphisms (AFLPs), mitochondrial sequences (800bp) as well as a molecular sexing marker. Overall, we demonstrate the utility of this novel noninvasive hair snare as a sampling technique for wildlife population biologists. We anticipate that this approach will be applicable to a variety of small mammals, opening up areas of investigation within natural populations, while minimizing impact to study organisms.

We present a noninvasive sampling approach to efficiently collect hair samples from elusive small mammals, as shown for the American pika. We demonstrate the utility of this method by extracting DNA from sampled hair and amplifying several types of molecular markers commonly used in studies of wildlife ecology and conservation.

Noninvasive genetic sampling approaches are becoming increasingly important to study wildlife populations. A number of studies have reported using ...

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an attractive model system to study organ development and tissue-specific signaling. Although hair follicle development is genetically tractable, fast and reproducible analysis of factors essential for this process remains a challenge. Here we describe a procedure to generate targeted overexpression or shRNA-mediated knockdown of factors using lentivirus in a tissue-specific manner. Using a modified version of a hair regeneration model 5, 6, 11, we can achieve robust gain- or loss-of-function analysis in primary mouse keratinocytes or dermal cells to facilitate study of epithelial-mesenchymal signaling pathways that lead to hair follicle morphogenesis. We describe how to isolate fresh primary mouse keratinocytes and dermal cells, which contain dermal papilla cells and their precursors, deliver lentivirus containing either shRNA or cDNA to one of the cell populations, and combine the cells to generate fully formed hair follicles on the backs of nude mice. This approach allows analysis of tissue-specific factors required to generate hair follicles within three weeks and provides a fast and convenient companion to existing genetic models.

Tissue-specific analysis of a hair follicle regeneration model using lentivirus to mediate gain- or loss-of-function.

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an ...

Analysis of Gene Function and Visualization of Cilia-Generated Fluid Flow in Kupffer's Vesicle

Internal organs such as the heart, brain, and gut develop left-right (LR) asymmetries that are critical for their normal functions1. Motile cilia are involved in establishing LR asymmetry in vertebrate embryos, including mouse, frog, and zebrafish2-6. These 'LR cilia' generate asymmetric fluid flow that is necessary to trigger a conserved asymmetric Nodal (TGF-&beta; superfamily) signaling cascade in the left lateral plate mesoderm, which is thought to provide LR patterning information for developing organs7. Thus, to understand mechanisms underlying LR patterning, it is essential to identify genes that regulate the organization of LR ciliated cells, the motility and length of LR cilia and their ability to generate robust asymmetric flow.
In the zebrafish embryo, LR cilia are located in Kupffer's vesicle (KV)2,4,5. KV is comprised of a single layer of monociliated epithelial cells that enclose a fluid-filled lumen. Fate mapping has shown that KV is derived from a group of ~20-30 cells known as dorsal forerunner cells (DFCs) that migrate at the dorsal blastoderm margin during epiboly stages8,9. During early somite stages, DFCs cluster and differentiate into ciliated epithelial cells to form KV in the tailbud of the embryo10,11. The ability to identify and track DFCs&mdash;in combination with optical transparency and rapid development of the zebrafish embryo&mdash;make zebrafish KV an excellent model system to study LR ciliated cells.
Interestingly, progenitors of the DFC/KV cell lineage retain cytoplasmic bridges between the yolk cell up to 4 hr post-fertilization (hpf), whereas cytoplasmic bridges between the yolk cell and other embryonic cells close after 2 hpf8. Taking advantage of these cytoplasmic bridges, we developed a stage-specific injection strategy to deliver morpholino oligonucleotides (MO) exclusively to DFCs and knockdown the function of a targeted gene in these cells12. This technique creates chimeric embryos in which gene function is knocked down in the DFC/KV lineage developing in the context of a wild-type embryo. To analyze asymmetric fluid flow in KV, we inject fluorescent microbeads into the KV lumen and record bead movement using videomicroscopy2. Fluid flow is easily visualized and can be quantified by tracking bead displacement over time.
Here, using the stage-specific DFC-targeted gene knockdown technique and injection of fluorescent microbeads into KV to visualize flow, we present a protocol that provides an effective approach to characterize the role of a particular gene during KV development and function.

Cilia-generated fluid flow in Kupffer&#x2019;s Vesicle (KV) controls left-right patterning of the zebrafish embryo. Here, we describe a technique to modulate gene function specifically in KV cells. In addition, we show how to deliver fluorescent beads into KV to visualize fluid flow.

Internal organs such as the  heart, brain, and gut develop left-right (LR) asymmetries that are critical for  their normal functions1. Motile cilia are ...

Prostaglandin Extraction and Analysis in Caenorhabditis elegans

Caenorhabditis elegans is emerging as a powerful animal model to study the biology of lipids1-9. Prostaglandins are an important class of eicosanoids, which are lipid signals derived from polyunsaturated fatty acids (PUFAs)10-14. These signalling molecules are difficult to study because of their low abundance and reactive nature. The characteristic feature of prostaglandins is a cyclopentane ring structure located within the fatty acid backbone. In mammals, prostaglandins can be formed through cyclooxygenase enzyme-dependent and -independent pathways10,15. C. elegans synthesizes a wide array of prostaglandins independent of cyclooxygenases6,16,17. A large class of F-series prostaglandins has been identified, but the study of eicosanoids is at an early stage with ample room for new discoveries. Here we describe a procedure for extracting and analyzing prostaglandins and other eicosanoids. Charged lipids are extracted from mass worm cultures using a liquid-liquid extraction technique and analyzed by liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The inclusion of deuterated analogs of prostaglandins, such as PGF2 &alpha;-d4 as an internal standard is recommended for quantitative analysis. Multiple reaction monitoring or MRM can be used to quantify and compare specific prostaglandin types between wild-type and mutant animals. Collision-induced decomposition or MS/MS can be used to obtain information on important structural features. Liquid chromatography mass spectrometry (LC-MS) survey scans of a selected mass range, such as m/z 315-360 can be used to evaluate global changes in prostaglandin levels. We provide examples of all three analyses. These methods will provide researchers with a toolset for discovering novel eicosanoids and delineating their metabolic pathways.

Prostaglandin Extraction and Analysis in Caenorhabditis elegans

In this paper, we describe an optimized procedure for extracting and analyzing prostaglandins and other eicosanoids from C. elegans using LC-MS/MS.

Caenorhabditis elegans is emerging as a powerful animal model to study the biology of lipids1-9. Prostaglandins are an important class of eicosanoids, ...

Extraction of Venom and Venom Gland Microdissections from Spiders for Proteomic and Transcriptomic Analyses

Venoms are chemically complex secretions typically comprising numerous proteins and peptides with varied physiological activities. Functional characterization of venom proteins has important biomedical applications, including the identification of drug leads or probes for cellular receptors. Spiders are the most species rich clade of venomous organisms, but the venoms of only a few species are well-understood, in part due to the difficulty associated with collecting minute quantities of venom from small animals. This paper presents a protocol for the collection of venom from spiders using electrical stimulation, demonstrating the procedure on the Western black widow (Latrodectus hesperus). The collected venom is useful for varied downstream analyses including direct protein identification via mass spectrometry, functional assays, and stimulation of venom gene expression for transcriptomic studies. This technique has the advantage over protocols that isolate venom from whole gland homogenates, which do not separate genuine venom components from cellular proteins that are not secreted as part of the venom. Representative results demonstrate the detection of known venom peptides from the collected sample using mass spectrometry. The venom collection procedure is followed by a protocol for dissecting spider venom glands, with results demonstrating that this leads to the characterization of venom-expressed proteins and peptides at the sequence level.

This article provides a protocol for the extraction of venom from spiders using electrical stimulation in order to 1) conduct proteomic characterization, 2) stimulate venom gland gene expression, and 3) perform functional studies of venoms. This is followed by a description of venom gland microdissections for gene expression studies.

Venoms are chemically complex secretions typically comprising numerous proteins and peptides with varied physiological activities. Functional ...

A New Technique for Quantitative Analysis of Hair Loss in Mice Using Grayscale Analysis

Alopecia is a common form of hair loss which can occur in many different conditions, including male-pattern hair loss, polycystic ovarian syndrome, and alopecia areata. Alopecia can also occur as a side effect of chemotherapy in cancer patients. In this study, our goal was to develop a consistent and reliable method to quantify hair loss in mice, which will allow investigators to accurately assess and compare new therapeutic approaches for these various forms of alopecia. The method utilizes a standard gel imager to obtain and process images of mice, measuring the light absorption, which occurs in rough proportion to the amount of black (or gray) hair on the mouse. Data that has been quantified in this fashion can then be analyzed using standard statistical techniques (i.e., ANOVA, T-test). This methodology was tested in mouse models of chemotherapy-induced alopecia, alopecia areata and alopecia from waxing. In this report, the detailed protocol is presented for performing these measurements, including validation data from C57BL/6 and C3H/HeJ strains of mice. This new technique offers a number of advantages, including relative simplicity of application, reliance on equipment which is readily available in most research laboratories, and applying an objective, quantitative assessment which is more robust than subjective evaluations. Improvements in quantification of hair growth in mice will improve study of alopecia models and facilitate evaluation of promising new therapies in preclinical studies.

Alopecia is a common form of hair loss which can occur in many different conditions, including as a side-effect of chemotherapy. We have developed a method to quantify hair loss in mice, utilizing a standard gel imager to perform a grayscale analysis, to facilitate study of promising new alopecia therapies.

Alopecia is a common form of hair loss which can occur in many different conditions, including male-pattern hair loss, polycystic ovarian syndrome, and ...

Complete Workflow for Analysis of Histone Post-translational Modifications Using Bottom-up Mass Spectrometry: From Histone Extraction to Data Analysis

Nucleosomes are the smallest structural unit of chromatin, composed of 147 base pairs of DNA wrapped around an octamer of histone proteins. Histone function is mediated by extensive post-translational modification by a myriad of nuclear proteins. These modifications are critical for nuclear integrity as they regulate chromatin structure and recruit enzymes involved in gene regulation, DNA repair and chromosome condensation. Even though a large part of the scientific community adopts antibody-based techniques to characterize histone PTM abundance, these approaches are low throughput and biased against hypermodified proteins, as the epitope might be obstructed by nearby modifications. This protocol describes the use of nano liquid chromatography (nLC) and mass spectrometry (MS) for accurate quantification of histone modifications. This method is designed to characterize a large variety of histone PTMs and the relative abundance of several histone variants within single analyses. In this protocol, histones are derivatized with propionic anhydride followed by digestion with trypsin to generate peptides of 5 - 20 aa in length. After digestion, the newly exposed N-termini of the histone peptides are derivatized to improve chromatographic retention during nLC-MS. This method allows for the relative quantification of histone PTMs spanning four orders of magnitude.

This protocol outlines a fully integrated workflow for characterizing histone post-translational modifications using mass spectrometry (MS). The workflow includes histone purification from cell cultures or tissues, histone derivatization and digestion, MS analysis using nano-flow liquid chromatography and instructions for data analysis. The protocol is designed for completion within 2 - 3 days.

Nucleosomes are the smallest structural unit of chromatin, composed of 147 base pairs of DNA wrapped around an octamer of histone proteins. Histone ...