This work was supported through start-up research funding for Edward Narayan through the Western Sydney University, School of Science and Health. The authors thank Jack Nakhoul for assistance with sample processing.

This project was performed under strict animal and human care guidelines. Animal ethics was granted by Western Sydney University (A12373). Additionally, a lab risk assessment and biosafety and radiation form were submitted and accepted by Western Sydney University to safely undertake this research (B12366).
NOTE: Koala fur samples for this project were obtained from the Adelaide Koala and Wildlife Hospital, located at 282 Anzac Highway, Plympton South Australia. Fur was taken from one koala which had been admitted to the hospital and euthanized due to their severe injuries. The deceased koala had been stored in a freezer within a body bag soon after death. After removing the deceased koala from the body bag, 1.2 g of fur was shaved from the nape of the neck using standard animal clippers. The fur was shaved as close as possible to the skin, so as to ensure the skin was not cut. Once shaved, the deceased koala was put back into the body bag and placed in the freezer. The fur was then placed in a pouch made of aluminum foil and stored below -20 &#176;C. In transit, the fur was kept at ambient temperature, and on arrival to the laboratory, the fur was stored at -80 &#176;C.
1. Koala fur cortisol extraction
<ol>
	<li>Remove the fur from storage at -80 &#176;C and allow time to thaw.</li>
	<li>Weigh the fur on a laboratory analytical precision balance.</li>
	<li>Place 60 mg of the fur into a pre-weighed and labelled 1.5 mL centrifuge tube and repeat until 18 tubes are filled. 
	NOTE: 18 fur sub-samples were used for this validation study.</li>
	<li>Add 1 mL of 100% high-performance liquid chromatography (HPLC) grade isopropanol to each tube using a pipette.</li>
	<li>Vortex samples for 30 s.</li>
	<li>Strain each sample using a 0.5 mm micro precision sieve so as to achieve separation of liquid and fur.</li>
	<li>Discard the liquid into a waste container.</li>
	<li>Place each fur sample into a labelled plastic weighing boat, then place into a vacuum desiccator, leave the fur to dry for 3 days.</li>
	<li>Once completely dry, place each sample into a labelled 1.5 mL microcentrifuge tube.</li>
	<li>Place each sample in a bead mill with 3 chrome steel beads (3.2 mm) and pulverize for 2 min at 30 shakes per second.</li>
	<li>Pipette 1.5 mL of the first extraction technique (100% analytical grade ethanol) into 6 1.5 mL microcentrifuge tubes containing the fur sample.</li>
	<li>Perform the same for 100% analytical grade methanol and 100% analytical grade isopropanol until eighteen 1.5 mL microcentrifuge tubes are filled.</li>
	<li>Cap each 1.5 mL microcentrifuge tube and incubate at room temperature (RT) with constant pulsating using a shaker for 3 h.</li>
	<li>Remove and strain samples using a 0.5 mm micro precision sieve.</li>
	<li>Transfer the liquid into a new, labelled 1.5 mL microcentrifuge tube with a pipette while ensuring that the fur is discarded appropriately.</li>
	<li>Completely dry solvent extract under a stream of N2 vapor under a fume-cupboard.</li>
	<li>Reconstitute the dried sample extract using 400 &#181;L of assay buffer (composition provided in the commercial cortisol kit; see Table of Materials) and 100 &#181;L of 100% analytical grade ethanol. 
	NOTE: Sample extracts can be stored at -80 .</li>
</ol>
2. Internal controls
<ol>
	<li>To make controls, make a pool of extracted samples with high hormone levels. To make this pool, select samples from animals with known exposure to stressor. For example, select samples from koalas that have been rescued from environmental trauma as they will generally display high cortisol hormone levels6.
	<ol>
		<li>To make the extract pool, take 20 &#181;L of extract from each sample (n = 10) until a total volume of 200 &#181;L is obtained. The extract pool can be stored at -80 C until assays. Run the pool in each assay as low or high internal controls (see step 2.2).</li>
	</ol>
	</li>
	<li>For the assay, use the pool to make stocks for low and high controls that bind at 70% (C1) and 30% (C2), respectively. Obtain the dilution factor for the 30% and 70% binding points from the parallelism graph for the extract against the cortisol standard (Figure 1). Use the assay buffer for dilution of sample pool. For example, use 60 &#181;L of the pool extract and 60 &#181;L of assay buffer for 1:2 dilution. 
	NOTE: For the methanol extract, the 30% binding point was at neat while 70% binding point was approximately 1:2 as per Figure 1. Thus, these provided the dilution factor for the internal controls (C1 and C2 respectively) for running within the assay.</li>
</ol>
3. Cortisol analysis in koala fur extracts
<ol>
	<li>Use a commercial cortisol kit (Table of Materials) and set up the 96 well strip plate including the samples, controls, cortisol standards, non-specific binding wells, and maximum binding wells following the supplier&#8217;s instructions. Use the plate layout sheet provided in the kit booklet to list the positions of samples, controls, and standards on the plate map. 
	NOTE: It is recommended that all samples, controls, and standards are run in duplicate to allow accuracy of results.</li>
	<li>Prepare samples. Follow the fur hormone extraction (section 1) to obtain 100% methanol extracted koala fur.</li>
	<li>Prepare reagents. Follow the procedure described in the commercial cortisol kit to prepare the reagents including (1) assay buffer, (2) wash Buffer, and (3) standards (compositions provided in the cortisol kit, Table of Materials).</li>
	<li>As per the instructions provided in the cortisol kit, pipet 50 &#181;L of samples or standards into wells in the plate. Pipet 75 &#181;L and 50 &#181;L of assay buffer into the non-specific binding (NSB) wells and the maximum binding (B0 or zero standard) wells, respectively.</li>
	<li>Add 25 &#181;L of the cortisol conjugate to each well using a repeater pipet. Then pipet 25 &#181;L of the cortisol antibody into each well, except the NSB wells. Gently tap the sides of the plate to ensure that the reagents are well mixed.</li>
	<li>Cover the plate with the plate sealer and shake at room temperature for 1 h (at slow speed) using an orbital shaker.</li>
	<li>Remove the plate sealer and aspirate the well plate by washing each well with 300 &#181;L of wash buffer 4 times.</li>
	<li>Dry the plate by tapping the plate on clean absorbent towels.</li>
	<li>Pipette 100 &#181;L of tetramethylbenzadine (TMB) substrate (composition provided in the cortisol kit, Table of Materials) to each well.</li>
	<li>Place the plate sealer on the well plate and incubate at RT for 30 min.</li>
	<li>Pipette 50 &#181;L of stop solution to each well.</li>
	<li>Place the well plate in a plate reader capable of reading 450 nm.</li>
	<li>To calculate the final hormone concentration, derive the final fur cortisol concentration in ng/mg of sample by multiplying the pg/mL hormone concentration with the final extract volume (0.5 mL) and dividing by the fur sample mass (60 mg).</li>
</ol>

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The authors have nothing to disclose.

There are a number of studies that use a range of techniques to detect cortisol in mammalian fur. This study presents results for the detection of cortisol in fur collected from a wild koala exposed to current anthropogenic stress. This ground-breaking study used fur to test which of the three commonly used solvents are best at extracting cortisol, a measure of chronic stress, from koala fur. Results showed that 100% methanol was the recommended solvent for cortisol extraction in this type of mammalian fur.
<p class=...

Australian ecosystems sustain human life through the provision of services including food and fiber among many other dynamic interactions1. Ironically, it is human activity that operates as the dominant driver of ecosystem disruption through biodiversity change2. Habitat fragmentation, known as the process of dividing large continuous habitats into small patches of land, isolated from each other, is the major anthropogenic biodiversity change threatening Australian ecosystems2. Habitat fragmentation modifies the structure and diversity of species composition in any given area, thus reducing the area of habitat necessary for these species to maintain viable populations2. The result of this is increased competition between species for resources including food, fuel, fiber, and water3. The destruction of Australian ecosystems through biodiversity change is having catastrophic consequences on many Australian native species1.
Australia&#39;s most iconic marsupial species, the koala (Phascolarctos cinereus), depends on Australian ecosystems remaining healthy for their survival4. The introduction of the European Settlement caused a rapid decline in Australian populations of koalas, as they were slaughtered for their pelts in pursuit of profit in a large export trade5. This practice was banned in the 1980&#39;s and populations of koalas were then able to stabilize5. However, exponential growth of the human population has resulted in this species competing for much of their habitat, and their survival is again under threat6. According to the International Union for the Conservation of Nature (IUCN), all populations of Australian koalas are listed as vulnerable to extinction with a decreasing population trend7. This listing is attributed to the uncertainty around relevant population parameters and marked variation in population trends for this species7. As the most iconic and endemic animals, koalas largely benefit the Australian economy through tourism (NSW Office of Environment and Heritage 2018). An estimation suggests that koala related tourism has generated approximately 9,000 jobs and contributes between $1.1 and $2.5 billion to the economy (NSW Office of Environment and Heritage 2018). The removal of any one species has the potential to be catastrophic, and can be seen in the steady decline of native Australian wildlife6. Additionally, the Australia economy will feel the ramifications if populations of Australian koalas continue to decline at the rate they are6.
It is suggested that prevalence of death and disease in response to habitat fragmentation is the result of chronic stress8. Already, twenty-four marsupial species have been declared extinct in Australia due to habitat fragmentation, with koalas following a similar trend8. The complexity of habitat fragmentation and biological systems is synergistic but can be unpacked through analysis of the stress response6. Generally, any disturbance in an animals natural surroundings activates a complex cascade of neurohormonal events, known as a &#39;fight or flight&#39;&#160;response9,10. This response to stress is a process that begins in the brain where the hypothalamic-pituitary-adrenal (HPA) axis is activated11. A component of the brain called the hypothalamus releases corticotrophin-releasing hormone (CRH), which then signals the anterior pituitary to release adrenocorticotrophic hormone (ACTH)11. This in turn stimulates the glucocorticoid secretion from the adrenal medulla. The body circulates glucocorticoids through the blood, which diverts the storage of glucose from glycogen and mobilizes glucose from stored glycogen11. This cascade of neurohormonal events is the response used by the animal to deal with unpredictable stimuli11. However, when glucocorticoids are being released and remain elevated for a prolonged period of time, the animal is considered to be experiencing chronic stress12,13. This process involves diverting energy away from other corporal bodily functions, as it is needed for ongoing glucocorticoid production13. As a result, chronic stress can prohibit growth, reproduction and immunity, all being key fitness traits required for survival14.
Measuring an animal&#39;s glucocorticoid production is a common indicator used to determine whether or not the animal is experiencing physiological stress15. To do so, glucocorticoids can be measured in blood plasma, serum, saliva, urine or faeces16. However, evidence suggests that hair is a much more effective indicator of chronic stress, as opposed to the aforementioned16. This is because hair is thought to incorporate blood-borne hormones during its growth phase; it is relatively stable; and any cortisol detected in hair reflects physiological stress experienced over the period of hair growth, which can be weeks through to months16. Furthermore, any collection of cortisol should be non-invasive in order to minimise the stress associated with capture and handling16. However, any stress experienced during this event would not impact glucocorticoid levels in hair16. There have been many studies that explore the proficiency of using hair to measure long-term stress in a number of animals, and include studies on reindeer, grizzly bears, rhesus monkeys, muskoxen, and brown bears17,18,19,20,21. Hair cortisol is usually extracted by first washing the sample to ensure sweat and sebum-derived cortisol deposited on the surface of the hair is not co-extracted with cortisol and then pulverizing the sample in a bead-beater22. After washing, the sample needs to be dried to ensure complete evaporation22. Finally, using a solvent, the sample can be extracted and reconstituted to facilitate the assay of cortisol22. The most common solvent used to extract cortisol from fur is methanol21,23; however, there are some studies that use ethanol and isopropanol in their cortisol extraction techniques. For example, a study that used ethanol was successful for extracting cortisol from human amniotic fluid24. Additionally, a study that used isopropanol was successful for extracting cortisol from human hair and nails25,26. For this reason, this study tested all three solvents (methanol, ethanol, and isopropanol) to determine which was the most successful for extraction of cortisol from samples of koala fur.
The primary objective of this study was to use current techniques to validate an optimal hormone extraction technique to be used as a non-invasive measure of cortisol from koala fur. This was achieved by testing three extraction solvents (methanol, ethanol, and isopropanol). We hypothesized that methanol will be the optimal solvent used for extracting cortisol from koala fur because it is the recommended solvent of extraction by Arbor assay cortisol kits27.&#160;&#160;&#160;&#160;&#160;

<table border="0" cellpadding="0" cellspacing="0" style="width:616px;" width="616">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Centrifuge Tubes</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">1.5 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Chrome Steel Beads</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">3.2 mm x 3</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">Cortisol Kit</td>
			<td style="width:72px;">Arbor Assays</td>
			<td style="width:119px;">K003-H1W</td>
			<td style="width:211px;">Manufactured in Michigan USA</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">DetectX Cortisol Enzyme Immunoassay Kit</td>
			<td style="width:72px;">Arbor Assays</td>
			<td style="width:119px;">K003-H5</td>
			<td style="width:211px;">Used first-time for cortisol testing in koala fur</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Ethanol</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">HPLC Grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Isopropanol</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">HPLC Grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Methanol</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">HPLC Grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Micro Pipette</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Micro Precision Sieve</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">0.5 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Microplate Reader</td>
			<td style="width:72px;">Bio Radi</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Microplate Washer</td>
			<td style="width:72px;">Bio Radi</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Orbital Shaker</td>
			<td style="width:72px;">Bio Line</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Plastic Weighing Boat</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Plate Sealer</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Precision Balance</td>
			<td style="width:72px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">Vortex Mixer</td>
			<td style="width:72px;">Eppendorf</td>
			<td style="width:119px;">n/a</td>
			<td style="width:211px;">n/a</td>
		</tr>
	</tbody>
</table>

cortisol measurement in koala (phascolarctos cinereus) fur

Optimal methods of hormone extraction used to measure stress in animals across sample types are not always the same. Australia&#39;s iconic marsupial species, the koala (Phascolarctos cinereus), faces prolonged exposure to anthropogenic-induced stressors and assessment of chronic stress in wild populations is urgently warranted. One of the most effective ways to measure chronic stress is through analyzing the glucocorticoid hormone cortisol in hair or fur, as it supports physiological and behavioral responses. This laboratory validation study aims to test current techniques to validate an optimal hormone extraction method to be used as a non-invasive measure of cortisol in koala fur. It is recognized that using non-invasive techniques to measure stress hormones is preferred over traditional, invasive techniques due to their ideal practical and ethical standpoints. Additionally, it is comparatively easier to acquire fur from koalas than it is to acquire samples of their blood. This study used samples of koala fur acquired from the Adelaide Koala and Wildlife Hospital to run a number of hormone extraction techniques in an attempt to validate an optimal cortisol extraction method. Results showed that 100% methanol provided the most optimal solvent extraction compared to 100% ethanol or 100% isopropanol based on parallelism results. In conclusion, this method of cortisol extraction from koala fur provided a reliable non-invasive assay that could be used to study chronic stress in koalas.

Assay detection of hormone metabolites of interest is determined using parallelism. Using a parallelism curve, the 50% binding point also determines the sample dilution factor on the standard curve (Figure 1). As shown in the parallelism graph (Figure 1), the 100% ethanol and 100% Isopropanol extracts did not provide parallel displacement against the cortisol standard. However, the 100% methanol extract provided parallel displacement against the cortisol standard. Dried extracts were run...

Watch this Scientific Journal Video about Cortisol Measurement in Koala Phascolarctos cinereus Fur at JoVE.com

Cortisol Measurement in Koala Phascolarctos cinereus Fur

We present a protocol to determine the optimal extraction solvent to measure cortisol from koala fur. The solvents used in this protocol are methanol, ethanol and isopropanol. Determining an optimal extraction solvent will aid in reliably measuring fur to determine the impact of chronic stress on koalas.

Cortisol Measurement in Koala (Phascolarctos cinereus) Fur

Optimal methods of hormone extraction used to measure stress in animals across sample types are not always the same. Australia&#39;s iconic marsupial ...

cortisol-measurement-in-koala-phascolarctos-cinereus-fur

Research

JoVE Journal

Biochemistry

10.6K Views.  Western Sydney University. We present a protocol to determine the optimal extraction solvent to measure cortisol from koala fur. The solvents used in this protocol are methanol, ethanol and isopropanol. Determining an optimal extraction solvent will aid in reliably measuring fur to determine the impact of chronic stress on koalas.

Video: Cortisol Measurement in Koala Phascolarctos cinereus Fur

Measurement of Basal and Forskolin-stimulated Lipolysis in Inguinal Adipose Fat Pads

Lipolysis is a process by which the lipid stored as triglycerides in adipose tissues are hydrolyzed into glycerol and fatty acids. This article describes the method for the measurement of basal and forskolin (FSK)-stimulated lipolysis in the inguinal fat pads isolated from wild type mice fed either normal chow diet (NCD), high fat diet (HFD) or a high fat diet containing 0.01% of capsaicin (CAP; transient receptor potential vanilloid subfamily 1 (TRPV1) agonist) for 32 weeks. The method described here for performing ex vivo lipolysis is adopted from Schweiger et al.1 We present a detailed protocol for measuring glycerol levels by UV-Visible (UV/VIS) spectrophotometry. The method described here can be used to successfully isolate inguinal fat pads for lipolysis measurements to obtain consistent results. The protocol described for inguinal fat pads can readily be extended to measure lipolysis in other tissues.

This protocol describes the method of determining basal and forskolin-stimulated lipolysis in inguinal fat pads obtained from normal chow diet (NCD) or high fat diet (HFD) &plusmn; capsaicin fed wild type mice. As an index for lipolysis, glycerol release was measured from inguinal adipose fat pads.

Lipolysis is a process by which the lipid stored as triglycerides in adipose tissues are hydrolyzed into glycerol and fatty acids. This article describes ...

Preparation of Keratin Hydrolysate from Chicken Feathers and Its Application in Cosmetics

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for skin-care cosmetics. The goals of the protocol are: (1) to process chicken feathers into KH by alkaline-enzymatic hydrolysis and purify it by dialysis, and (2) to test if adding KH into an ointment base (OB) increases hydration of the skin and improves skin barrier function by diminishing transepidermal water loss (TEWL). During alkaline-enzymatic hydrolysis feathers are first incubated at a higher temperature in an alkaline environment and then, under mild conditions, hydrolyzed with proteolytic enzyme. The solution of KH is dialyzed, vacuum dried, and milled to a fine powder. Cosmetic formulations comprising from oil in water emulsion (O/W) containing 2, 4, and 6 weight% of KH (based on the weight of the OB) are prepared. Testing the moisturizing properties of KH is carried out on 10 men and 10 women at time intervals of 1, 2, 3, 4, 24, and 48 h. Tested formulations are spread at degreased volar forearm sites. The skin hydration of stratum corneum (SC) is assessed by measuring capacitance of the skin, which is one of the most world-wide used and simple methods. TEWL is based on measuring the quantity of water transported per a defined area and period of time from the skin. Both methods are fully non-invasive. KH makes for an excellent occlusive; depending on the addition of KH into OB, it brings about a 30% reduction in TEWL after application. KH also functions as a humectant, as it binds water from the lower layers of the epidermis to the SC; at the optimum KH addition in the OB, up to 19% rise in hydration in men and 22% rise in women occurs.

The goal of the protocol is to prepare keratin hydrolysate from chicken feathers by alkaline-enzymatic hydrolysis and to test whether adding keratin hydrolysate into a cosmetics ointment base improves skin barrier function (heightening hydration and diminishing transepidermal water loss). Tests are conducted on men and woman volunteers.

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for ...

Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases

It has been reported that mitochondria can contain up to 12 enzymatic sources of reactive oxygen species (ROS). A majority of these sites include flavin-dependent respiratory complexes and dehydrogenases that produce a mixture of superoxide (O2&#9679;-) and hydrogen peroxide (H2O2). Accurate quantification of the ROS-producing potential of individual sites in isolated mitochondria can be challenging due to the presence of antioxidant defense systems&#160;and side reactions that also form O2&#9679;-/H2O2. Use&#160;of nonspecific inhibitors that can disrupt mitochondrial bioenergetics can also compromise measurements by altering&#160;ROS release from other sites of production. Here, we present an easy method for the simultaneous measurement of H2O2 release and nicotinamide adenine dinucleotide (NADH) production by purified flavin-linked dehydrogenases. For our purposes here, we have used purified pyruvate dehydrogenase complex (PDHC) and &#945;-ketoglutarate dehydrogenase complex (KGDHC) of porcine heart origin as examples. This method allows for an accurate measure of native H2O2 release rates by individual sites of production by eliminating other potential sources of ROS and antioxidant systems. In addition, this method allows for a direct comparison of the relationship between H2O2 release and enzyme activity and the screening of the effectiveness and selectivity of inhibitors for ROS production. Overall, this approach can allow for the in-depth assessment of native rates of ROS release for individual enzymes prior to conducting more sophisticated experiments with isolated mitochondria or permeabilized muscle fiber.

Mitochondria contain several flavin-dependent enzymes that can produce reactive oxygen species (ROS). Monitoring ROS release from individual sites in mitochondria is challenging due to unwanted side reactions. We present an easy, inexpensive method for direct assessment of native rates for ROS release using purified flavoenzymes and microplate fluorometry.

It has been reported that mitochondria can contain up to 12 enzymatic sources of reactive oxygen species (ROS). A majority of these sites include ...

Measurement of Mitochondrial Oxygen Consumption in Permeabilized Fibers of Drosophila Using Minimal Amounts of Tissue

The fruit fly, Drosophila melanogaster, represents an emerging model for the study of metabolism. Indeed, drosophila have structures homologous to human organs, possess highly conserved metabolic pathways and have a relatively short lifespan that allows the study of different fundamental mechanisms in a short period of time. It is, however, surprising that one of the mechanisms essential for cellular metabolism, the mitochondrial respiration, has not been thoroughly investigated in this model. It is likely because the measure of the mitochondrial respiration in Drosophila usually requires a very large number of individuals and the results obtained are not highly reproducible. Here, a method allowing the precise measurement of mitochondrial oxygen consumption using minimal amounts of tissue from Drosophila is described. In this method, the thoraxes are dissected and permeabilized both mechanically with sharp forceps and chemically with saponin, allowing different compounds to cross the cell membrane and modulate the mitochondrial respiration. After permeabilization, a protocol is performed to evaluate the capacity of the different complexes of the electron transport system (ETS) to oxidize different substrates, as well as their response to an uncoupler and to several inhibitors. This method presents many advantages compared to methods using mitochondrial isolations, as it is more physiologically relevant because the mitochondria are still interacting with the other cellular components and the mitochondrial morphology is conserved. Moreover, sample preparations are faster, and the results obtained are highly reproducible. By combining the advantages of Drosophila as a model for the study of metabolism with the evaluation of mitochondrial respiration, important new insights can be unveiled, especially when the flies are experiencing different environmental or pathophysiological conditions.

In this paper, a method to measure oxygen consumption using high-resolution respirometry in permeabilized thoraxes of Drosophila is described. This technique requires a minimal amount of tissue compared to the classic mitochondrial isolation technique and the results obtained are more physiologically relevant.

The fruit fly, Drosophila melanogaster, represents an emerging model for the study of metabolism. Indeed, drosophila have structures homologous to human ...

In Situ Measurement and Correlation of Cell Density and Light Emission of Bioluminescent Bacteria

There is a considerable number of bacterial species capable of emitting light. All of them share the same gene cluster, namely the lux operon. Despite this similarity, these bacteria show extreme variations in characteristics like growth behavior, intensity of light emission or regulation of bioluminescence. The method presented here is a newly developed assay that combines recording of cell growth and bioluminescent light emission intensity over time utilizing a plate reader. The resulting growth and light emission characteristics can be linked to important features of the respective bacterial strain, such as quorum sensing regulation. The cultivation of a range of bioluminescent bacteria requires a specific medium (e.g., artificial sea water medium) and defined temperatures. The easy to handle, non-bioluminescent standard-research bacterium Escherichia coli (E. coli), on the other hand, can be cultivated inexpensively in high quantities in laboratory scale. Exploiting E. coli by introducing a plasmid containing the whole lux operon can simplify experimental conditions and additionally opens up many possibilities for future applications. The expression of all lux genes utilizing an E. coli expression strain was achieved by construction of an expression plasmid via Gibson cloning and insertion of four fragments containing seven lux genes and three rib genes of the lux-rib operon into a pET28a vector. E. coli based lux gene expression can be induced and controlled via Isopropyl-&#946;-D-thiogalactopyranosid (IPTG) addition resulting in bioluminescent E. coli cells. The advantages of this system are to avoid quorum sensing regulation restrictions and complex medium compositions along with non-standard growth conditions, such as defined temperatures. This system enables analysis of lux genes and their interplay, by the exclusion of the respective gene from the lux operon, or even addition of novel genes, exchanging the luxAB genes from one bacterial strain by another, or analyzing protein complexes, such as luxCDE.

In Situ Measurement and Correlation of Cell Density and Light Emission of Bioluminescent Bacteria

Bioluminescent bacteria regulate light production through a variety of mechanisms, such as quorum sensing. This novel method allows the in situ investigation of bioluminescence and the correlation of light emission to cell density. An artificial bioluminescent Escherichia coli system allows the characterization of lux operons, Lux proteins, and their interplay.

There is a considerable number of bacterial species capable of emitting light. All of them share the same gene cluster, namely the lux operon. Despite ...

Measurement of Ion Concentration in the Unstirred Boundary Layer with Open Patch-Clamp Pipette: Implications in Control of Ion Channels by Fluid Flow

Fluid flow is an important environmental stimulus that controls many physiological and pathological processes, such as fluid flow-induced vasodilation. Although the molecular mechanisms for the biological responses to fluid flow/shear force are not fully understood, fluid flow-mediated regulation of ion channel gating may contribute critically. Therefore, fluid flow/shear force sensitivity of ion channels has been studied using the patch-clamp technique. However, depending on the experimental protocol, the outcomes and interpretation of data can be erroneous. Here, we present experimental and theoretical evidence for fluid flow-related errors and provide methods for estimating, preventing, and correcting these errors. Changes in junction potential between the Ag/AgCl reference electrode and bathing fluid were measured with an open pipette filled with 3 M KCl. Fluid flow could then shift the liquid/metal junction potential to approximately 7 mV. Conversely, by measuring the voltage shift induced by fluid flow, we estimated the ion concentration in the unstirred boundary layer. In the static condition, the real ion concentrations adjacent to the Ag/AgCl reference electrode or ion channel inlet at the cell-membrane surface can reach as low as approximately 30% of that in the flow condition. Placing an agarose 3 M KCl bridge between the bathing fluid and reference electrode may have prevented this problem of junction potential shifting. However, the unstirred layer effect adjacent to the cell membrane surface could not be fixed in this way. Here, we provide a method for measuring real ion concentrations in the unstirred boundary layer with an open patch-clamp pipette, emphasizing the importance of using an agarose salt-bridge while studying fluid flow-induced regulation of ion currents. Therefore, this novel approach, which takes into consideration the real concentrations of ions in the unstirred boundary layer, may provide useful insight on the experimental design and data interpretation related to fluid shear stress regulation of ion channels.

Mechanosensitive ion channels are often studied in terms of fluid flow/shear force sensitivity with patch-clamp recording. However, depending on the experimental protocol, the outcome on fluid flow-regulations of ion channels can be erroneous. Here, we provide methods for preventing and correcting such errors with a theoretical basis.

Fluid flow is an important environmental stimulus that controls many physiological and pathological processes, such as fluid flow-induced vasodilation. ...

Affinity Purification of Chloroplast Translocon Protein Complexes Using the TAP Tag

Chloroplast biogenesis requires the import of thousands of nucleus-encoded proteins into the plastid. The import of these proteins depends on the translocon at the outer (TOC) and inner (TIC) chloroplast membranes. The TOC and TIC complexes are multimeric and probably contain yet unknown components. One of the main goals in the field is to establish the complete inventory of TOC and TIC components. For the isolation of TOC-TIC complexes and the identification of new components, the preprotein receptor TOC159 has been modified N-terminally by the addition of the tandem affinity purification (TAP) tag resulting in TAP-TOC159. The TAP-tag is designed for two sequential affinity purification steps (hence "tandem affinity"). The TAP-tag used in these studies consists of a N-terminal IgG-binding domain derived from Staphylococcus aureus Protein A (ProtA) followed by a calmodulin-binding peptide (CBP). Between these two affinity tags, a tobacco etch virus (TEV) protease cleavage site has been included. Therefore, TEV protease can be used for gentle elution of TOC159-containing complexes after binding to IgG beads. In the protocol presented here, the second Calmodulin-affinity purification step was omitted. The purification protocol starts with the preparation and solubilization of total cellular membranes. After the detergent-treatment, the solubilized membrane proteins are incubated with IgG beads for the immunoisolation of TAP-TOC159-containing complexes. Upon binding and extensive washing, TAP-TOC159 containing complexes are cleaved and released from the IgG beads using the TEV protease whereby the S. aureus IgG-binding domain is removed. Western blotting of the isolated TOC159-containing complexes can be used to confirm the presence of known or suspected TOC and TIC proteins. More importantly, the TOC159-containing complexes have been used successfully to identify new components of the TOC and TIC complexes by mass spectrometry. The protocol that we present potentially allows the efficient isolation of any membrane-bound protein complex to be used for the identification of yet unknown components by mass spectrometry.

We here present a proven and tested protocol for the purification of chloroplast protein import complexes (TOC-TIC complex) using the TAP-tag. The one-step affinity-isolation protocol can potentially be applied to any protein and be used to identify new interaction partners by mass spectrometry.

Chloroplast biogenesis requires the import of thousands of nucleus-encoded proteins into the plastid. The import of these proteins depends on the ...

Direct Measurement of KDM1A Target Engagement Using Chemoprobe-based Immunoassays

The assessment of the target engagement, defined as the interaction of a drug with the protein it was designed for, is a basic requirement for the interpretation of the biological activity of any compound in drug development or in basic research projects. In epigenetics, target engagement is most often assessed by the analysis of proxy markers instead of measuring the union of the compound to the target. Downstream biological readouts that have been analyzed include the histone mark modulation or gene expression changes. KDM1A is a lysine demethylase that removes methyl groups from mono- and dimethylated H3K4, a modification associated with the silencing of gene expression. Modulation of the proxy markers is dependent on the cell type and function of the genetic make-up of the cells investigated, which can make interpretation and cross-case comparison quite difficult. To circumvent these problems, a versatile protocol is presented to assess the dose effects and dynamics of the direct KDM1A target engagement. The assay described makes use of a KDM1A chemoprobe to capture and quantify uninhibited enzyme, can be broadly applied to cells or tissue samples without the need for genetic modification, has an excellent window of detection, and can be used both for basic research and analysis of clinical samples.

Here, we present a protocol to measure KDM1A target engagement in a human or animal cell, tissue or blood samples treated with KDM1A inhibitors. The protocol employs chemoprobe tagging of the free KDM1A enzyme and direct quantification of the target occupation using chemoprobe-based immunoassays and can be used in preclinical and clinical studies.

The assessment of the target engagement, defined as the interaction of a drug with the protein it was designed for, is a basic requirement for the ...

Measurement of Fatty Acid &#946;-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes

Fatty acid &#946;-oxidation is a key metabolic pathway to meet the energy demands of the liver and provide substrates and cofactors for additional processes, such as ketogenesis and gluconeogenesis, which are essential to maintain whole-body glucose homeostasis and support extra-hepatic organ function in the fasted state. Fatty acid &#946;-oxidation occurs within the mitochondria and peroxisomes and is regulated through multiple mechanisms, including the uptake and activation of fatty acids, enzyme expression levels, and availability of cofactors such as coenzyme A and NAD+. In assays that measure fatty acid &#946;-oxidation in liver homogenates, cell lysis and the common addition of supraphysiological levels of cofactors mask the effects of these regulatory mechanisms. Furthermore, the integrity of the organelles in the homogenates is hard to control and can vary significantly between preparations. The measurement of fatty acid &#946;-oxidation in intact primary hepatocytes overcomes the above pitfalls. This protocol describes a method for the measurement of fatty acid &#946;-oxidation in a suspension of freshly isolated primary mouse hepatocytes incubated with 14C-labeled palmitic acid. By avoiding hours to days of culture, this method has the advantage of better preserving the protein expression levels and metabolic pathway activity of the original liver, including the activation of fatty acid &#946;-oxidation observed in hepatocytes isolated from fasted mice compared to fed mice.

Fatty acid &#946;-oxidation is an essential metabolic pathway responsible for generating energy in many different cell types, including hepatocytes. Here, we describe a method to measure fatty acid &#946;-oxidation in freshly isolated primary hepatocytes using 14C-labeled palmitic acid.

Fatty acid &#946;-oxidation is a key metabolic pathway to meet the energy demands of the liver and provide substrates and cofactors for additional ...

Time-resolved F&#246;rster Resonance Energy Transfer Assays for Measurement of Endogenous Phosphorylated STAT Proteins in Human Cells

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway plays a crucial role in mediating cellular responses to cytokines and growth factors. STAT proteins are activated by tyrosine phosphorylation mediated mainly by JAKs. The abnormal activation of STAT signaling pathways is implicated in many human diseases, especially cancer and immune-related conditions. Therefore, the ability to monitor STAT protein phosphorylation within the native cell signaling environment is important for both academic and drug discovery research. The traditional assay formats available to quantify phosphorylated STAT proteins include western blotting and the enzyme-linked immunosorbent assay (ELISA). These heterogeneous methods are labor-intensive, low-throughput, and often not reliable (specific) in the case of western blotting. Homogeneous (no-wash) methods are available but remain expensive. 
Here, detailed protocols are provided for the sensitive, robust, and cost-effective measurement in a 384-well format of endogenous levels of phosphorylated STAT1 (Y701), STAT3 (Y705), STAT4 (Y693), STAT5 (Y694/Y699), and STAT6 (Y641) in cell lysates from adherent or suspension cells using the novel THUNDER time-resolved F&#246;rster resonance energy transfer (TR-FRET) platform. The workflow for the cellular assay is simple, fast, and designed for high-throughput screening (HTS). The assay protocol is flexible, uses a low-volume sample (15 &#181;L), requires only one reagent addition step, and can be adapted to low-throughput and high-throughput applications. Each phospho-STAT sandwich immunoassay is validated under optimized conditions with known agonists and inhibitors and generates the expected pharmacology and Z'-factor values. As TR-FRET assays are ratiometric and require no washing steps, they provide much better reproducibility than traditional approaches. Together, this suite of assays provides new cost-effective tools for a more comprehensive analysis of specific phosphorylated STAT proteins following cell treatment and the screening and characterization of specific and selective modulators of the JAK/STAT signaling pathway.

Time-resolved F&#246;rster resonance energy transfer cell-based assay protocols are described for the simple, specific, sensitive, and robust quantification of endogenous phosphorylated signal transducer and activator of transcription (STAT) 1/3/4/5/6 proteins in cell lysates in a 384-well format.

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway plays a crucial role in mediating cellular responses to ...