We thank Dvir Mintz DVM and the veterinary and husbandry staff in the animal facility, as well as members of our group, for fruitful discussions. This study was supported by an Israel Science Foundation grant 1541/21 awarded to D.B.Z. D.B.Z. is a Zuckerman STEM faculty.

The experiments were approved by the Hebrew University&#39;s Institutional Animal Care and Use Committee (IACUC).
NOTE: All tools must be sterilized, and handling of the cannula must be performed using a sterile technique. The protocol below is fine-tuned to a specific CGM. The protocol can be adapted to other CGMs.
1. Analgesic administration before the procedure
<ol>
	<li>Administer 5% dextrose and 0.45% saline with meloxicam at 5 mg/kg body weight subcutaneously.</li>
</ol>
2. Anesthesia administration
<ol>
	<li>Place the mouse in the induction chamber, closing the lid tightly. Set the induction of anesthesia in the induction chamber at 3% isoflurane at a flow rate of 500 mL/min.</li>
	<li>Once the mouse is unresponsive, remove the mouse from the chamber, and fit the nose cone to the mouse. Confirm the anesthesia level with an interdigital pinch. Set the concentration to 1%-1.5% isoflurane and the flow rate to 100 mL/min in a mouse weighing 30 g.</li>
	<li>Apply ophthalmic ointment to the eyes to prevent dryness during anesthesia.</li>
</ol>
3. Sensor preparation
<ol>
	<li>Mount the sensor onto the sensor mounting device to expose the sensor&#39;s tape and cannula side (Figure 1A). Be cautious since the needle is inserted into the cannula and exposed.</li>
	<li>Suture two 5-0 taper point sutures to the tape on both sides of the cannula (Figure 1A).</li>
</ol>
4. Hair removal and disinfection
<ol>
	<li>Shave an area of approximately 4 cm x 4 cm on the midline of the back of the mouse.</li>
	<li>Administer a depilatory cream to the shaved area to ensure complete hair removal.</li>
	<li>Wipe the skin, and disinfect it using an antiseptic solution containing 2% chlorhexidine gluconate and 70% isopropyl alcohol.</li>
</ol>
5. Dorsal skin preparation
<ol>
	<li>Make a 2 mm incision in the center of the shaved area above the spine using sharp scissors (Figure 1B).</li>
	<li>Briefly, insert small forceps with a blunt edge under the skin to form a small subcutaneous pocket so that the cannula can be inserted easily into the subcutaneous pocket (Figure 1B).</li>
	<li>Pass a suture from step 3.2 through the skin on each side of the incision (Figure 1C).</li>
</ol>
6. Sensor insertion
<ol>
	<li>Remove the sensor completely from the sensor mounting device (the cannula is void from the needle), and hold the sensor with forceps to keep the surrounding tape from sticking to itself.</li>
	<li>Carefully insert the cannula into the subcutaneous pocket.</li>
	<li>Pull the sutures on each side, and tighten and tie them to attach the sensor firmly in place, thus preventing the cannula from slipping out from the subcutaneous pocket once the adhesive tape loosens over time.</li>
</ol>
7. Sensor attachment and suturing
<ol>
	<li>Attach the sensor to the back firmly by tying the inner sutures and using the adhesive tape surrounding the sensor.</li>
	<li>Make eight discontinuous sutures around the sensor, attaching the border of the sensor&#39;s tape to the skin (Figure 1D).</li>
</ol>
8. Activation of the reader
<ol>
	<li>Once the sensor has been inserted, activate the reader by turning on the reader, pressing Start New Sensor, and swiping the sensor according to the manufacturer&#39;s instructions.</li>
	<li>The first reading can only be taken a few minutes after installing the CGM. In the case of this CGM, the first reading can be taken after 60 min.</li>
</ol>
9. Reading results
<ol>
	<li>Place the reader close to the mouse (there is no need to touch it). All data stored in the sensor are transmitted to the reader. 
	&#8203;NOTE: Different CGM devices may differ in the period of historic data saving capacity. In the case of this CGM, a maximum of 8 h can be stored between two readings.</li>
</ol>
10. Removing the sensor
<ol>
	<li>Anesthetize the mouse (see section 2).</li>
	<li>Cut the sutures connecting the sensor to the back of the mouse using sharp scissors.</li>
	<li>Remove and cut the sutures at the incision by gently removing the sensor.</li>
	<li>If necessary, use a single suture to close the incision in the back of the mouse.</li>
</ol>
11. Data analysis
<ol>
	<li>Data download: Download the data as per the instructions provided by the CGM manufacturer. 
	&#8203;NOTE: Each CGM has a different format, which may or may not be easily accessible to the user. This is an important consideration in choosing the CGM.</li>
	<li>For analysis with the software provided, format the data according to the instructions in the readme file on Github (https://github.com/mika-littor/CGM-in-Mice-Analysis.git).</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64743/64743fig01.jpg" /> 
Figure 1: Attachment of the sensor to the mouse. (A) Two sutures marked by red arrows are passed through the sensor tape on both sides of the cannula on the bottom side of the CGM sensor, marked by a white arrow. (B) A small 2 mm incision is made in the center of the shaved area along the spine using sharp scissors. Small forceps with a blunt edge are briefly inserted under the skin to form a small subcutaneous pocket so that the cannula can be inserted subcutaneously. (C) The same sutures from A are passed subcutaneously on each side of the incision. The red arrows mark the sutures attached to the sensor as in A, the blue arrows mark the location the sutures passed through to the skin in the back of the mouse, and the black arrow shows the incision. (D) After the cannula is inserted, the inner sutures are tightened and tied close to the incision to secure the CGM. The sensor is then sutured to the skin. <a href="https://www.jove.com/files/ftp_upload/64743/64743fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<ol>
	<li>Polonsky, K. 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+past+200+years+in+diabetes.">The past 200 years in diabetes.</a> New England Journal of Medicine. 367 (14), 1332-1340 (2012).</li><li>Rees, D. A., Alcolado, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+diabetes+mellitus.">Animal models of diabetes mellitus.</a> Diabetic Medicine. 22 (4), 359-370 (2005).</li><li>Pearson, J. A., Wong, F. S., Wen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+importance+of+the+non-obese+diabetic+(NOD)+mouse+model+in+autoimmune+diabetes.">The importance of the non-obese diabetic (NOD) mouse model in autoimmune diabetes.</a> Journal of Autoimmunity. 66, 76-88 (2016).</li><li>Heydemann, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+overview+of+murine+high+fat+diet+as+a+model+for+Type+2+diabetes+mellitus.">An overview of murine high fat diet as a model for Type 2 diabetes mellitus.</a> Journal of Diabetes Research. 2016, 2902351 (2016).</li><li>Kennard, M. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+mice+in+diabetes+research:+The+impact+of+experimental+protocols.">The use of mice in diabetes research: The impact of experimental protocols.</a> Diabetic Medicine. 38 (12), 14705 (2021).</li><li>Klueh, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+glucose+monitoring+in+normal+mice+and+mice+with+prediabetes+and+diabetes.">Continuous glucose monitoring in normal mice and mice with prediabetes and diabetes.</a> Diabetes Technology and Therapeutics. 8 (3), 402-412 (2006).</li><li>Wuyts, C., Simoens, C., Pinto, S., Philippaert, K., Vennekens, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+glucose+monitoring+during+pregnancy+in+healthy+mice.">Continuous glucose monitoring during pregnancy in healthy mice.</a> Scientific Reports. 11, 4450 (2021).</li><li>Korstanje, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+glucose+monitoring+in+female+NOD+mice+reveals+daily+rhythms+and+a+negative+correlation+with+body+temperature.">Continuous glucose monitoring in female NOD mice reveals daily rhythms and a negative correlation with body temperature.</a> Endocrinology. 158 (9), 2707-2712 (2017).</li><li>Han, B. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Markers+of+glycemic+control+in+the+mouse:+Comparisons+of+6-h-and+overnight-fasted+blood+glucoses+to+Hb+A1c.">Markers of glycemic control in the mouse: Comparisons of 6-h-and overnight-fasted blood glucoses to Hb A1c.</a> American Journal of Physiology - Endocrinology and Metabolism. 295 (4), 981-986 (2008).</li><li>Xie, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+measurement+noise+in+a+continuous+glucose+monitor+by+coating+the+sensor+with+a+zwitterionic+polymer.">Reduction of measurement noise in a continuous glucose monitor by coating the sensor with a zwitterionic polymer.</a> Nature Biomedical Engineering. 2 (12), 894-906 (2018).</li><li>Van Der Meulen, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urocortin3+mediates+somatostatin-dependent+negative+feedback+control+of+insulin+secretion.">Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion.</a> Nature Medicine. 21 (7), 769-776 (2015).</li><li>Peterson, Q. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+the+generation+of+human+stem+cell-derived+alpha+cells.">A method for the generation of human stem cell-derived alpha cells.</a> Nature Communications. 11, 2241 (2020).</li><li>Klueh, U., Liu, Z., Feldman, B., Kreutzer, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interstitial+fluid+physiology+as+it+relates+to+glucose+monitoring+technologies:+Importance+of+Interleukin-1+and+Interleukin-1+receptor+antagonist+in+short-term+glucose+sensor+function+in+vivo.">Interstitial fluid physiology as it relates to glucose monitoring technologies: Importance of Interleukin-1 and Interleukin-1 receptor antagonist in short-term glucose sensor function in vivo.</a> Journal of Diabetes Science and Technology. 4 (5), 1073 (2010).</li><li>Klueh, U., Antar, O., Qiao, Y., Kreutzer, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+interleukin-1/interleukin-1+receptor+antagonist+family+of+cytokines+in+long-term+continuous+glucose+monitoring+in+vivo.">Role of interleukin-1/interleukin-1 receptor antagonist family of cytokines in long-term continuous glucose monitoring in vivo.</a> Journal of Diabetes Science and Technology. 7 (6), 1538 (2013).</li><li>Klueh, U., Kaur, M., Qiao, Y., Kreutzer, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+role+of+tissue+mast+cells+in+controlling+long-term+glucose+sensor+function+in+vivo.">Critical role of tissue mast cells in controlling long-term glucose sensor function in vivo.</a> Biomaterials. 31 (16), 4540-4551 (2010).</li><li>Kogot-Levin, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+the+metabolic+reprogramming+induced+by+sodium-glucose+cotransporter+2+inhibition.">Mapping the metabolic reprogramming induced by sodium-glucose cotransporter 2 inhibition.</a> JCI Insight. , 164296 (2023).</li></ol>

The authors have no conflicts of interest to disclose.

This protocol offers a simple, inexpensive method to monitor glucose levels in mice that does not require challenging microsurgery and does not involve bleeding or handling the mice. The method is easy to implement in every facility and does not cause mortality, pain, or excessive discomfort to the mice. The most critical step in the protocol is inserting the cannula of the glucose sensor under the skin of the mouse. The addition of a few sutures allows the cannula to stay in place for a longer time. The sensors are smal...

Diabetes mellitus (DM) is a devastating disease characterized by high blood glucose levels. Type 1 DM can be a result of an autoimmune attack on the insulin-producing beta cells in the pancreas. Type 2 DM and gestational DM, on the other hand, are characterized by a failure of the beta cells to secrete sufficient insulin in response to a rise in glucose levels1. The mouse is a common model organism used to study DM since it has similar physiology, and its normal glucose levels are close to those of humans. Furthermore, specific mouse strains may develop DM due to mutations in key signaling pathways or following exposure to specific diets, which enables disease modeling2,3,4.
Blood glucose is commonly measured in mice using glucometers designed for patients by extracting a small drop of blood (1-2 &#181;L) from the tip of the tail of the mouse. This method causes stress and requires handling of the mouse, which affects the glucose levels and prohibits the measurement of blood glucose levels in freely behaving mice or when the researcher is not close by5. Bleeding the mice may cause stress to nearby mice, particularly to mice of the same cage whose glycemia has not been measured yet, thus affecting the results. Mice respond differently depending on the handler, and the person measuring glucose may affect the glucose levels of the mice. These pitfalls call for careful experimental design and underlie some inconsistencies between experiments.
It is possible to measure glucose in freely moving mice with no bleeding by implanting glucose sensors into the aortic arch of the mice using state-of-the-art telemetry6. The resulting measurements are very good and can be sustained over a long period, but it is challenging to implant these sensors, and the telemetry system is expensive, leading to a moderate adoption of this methodology and no adoption in non-specialized labs. Subcutaneous or other glucose sensors that are tailored to the dimensions of the mice and their physiology have been developed in recent years, but these again require highly skilled experts and are in some cases costly6,7,8,9,10.
Commercial continuous glucose monitors (CGMs) that were originally developed to monitor the glucose levels of DM patients offer another option to measure glucose in freely moving mice, with lower cost and technical expertise requirements than implanted probes. Such probes have been used in basic research by a few labs5,11,12,13,14,15&#160;including our colleagues who used this protocol16. These devices typically include a sensor, a mounting device, a receiver, and a software application. The sensor has a cannula guiding the enzymatic glucosensor, adhesive tape, an energy source, short-term memory, and a wireless communication module that stores and sends the data to the receiver. The receiver can show the current glucose levels and sends the data to a server; this receiver can be a cellphone. The software application provides data for the patient and the medical care team on the glycaemia of the patient. In patients, the sensor is attached easily using the mounting device. The cannula is inserted subcutaneously by pressing the mounting device against the skin, and the sensor stays in place with the help of adhesive tape.
This is a detailed protocol for adapting a commercial CGM device to measure glucose levels in mice. This protocol describes how to surgically insert the glucose sensor and attach it to the mouse. Scripts for basic data analysis and data visualization are provided. The potential pitfalls, troubleshooting, and examples of standard results are provided. The protocol below is specific for a certain CGM but can be easily adapted to other types of commercial CGMs as they become available.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2%&#160; Chlorhexidine Gluconate and 70%&#160; Isopropyl Alcohol</td>
			<td>3M</td>
			<td>ID&#160;7000136290</td>
			<td></td>
		</tr>
		<tr>
			<td>5% Dextrose and 0.45% Sodium Chloride Injection, USP</td>
			<td>Braun</td>
			<td>L6120</td>
			<td></td>
		</tr>
		<tr>
			<td>Castroviejo needle holder</td>
			<td>FST</td>
			<td>12061-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Extra Fine Bonn scissors</td>
			<td>FST</td>
			<td>14084-08</td>
			<td></td>
		</tr>
		<tr>
			<td>FreeStyle Libre 1 reader</td>
			<td>Abbott</td>
			<td>ART27543&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>FreeStyle Libre sensor</td>
			<td>Abbott</td>
			<td>ART36687</td>
			<td></td>
		</tr>
		<tr>
			<td>FreeStyle Libre sensor applicator</td>
			<td>Abbott</td>
			<td>ART36787</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze pads</td>
			<td>Sion medical</td>
			<td>PC912017</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe Forceps</td>
			<td>FST</td>
			<td>11052-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Hair Removal Cream</td>
			<td>Veet</td>
			<td>3116523</td>
			<td></td>
		</tr>
		<tr>
			<td>High-fat high-sucrose diet</td>
			<td>Envigo Teklad diets</td>
			<td>TD.08811</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane, USP Terrell</td>
			<td>Piramal</td>
			<td>26675-46-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Meloxicam 5 mg/mL</td>
			<td>Chanelle Pharma</td>
			<td>08749/5024</td>
			<td></td>
		</tr>
		<tr>
			<td>MiniARCO Clipper kit</td>
			<td>Moser</td>
			<td>CL8787-KIT</td>
			<td></td>
		</tr>
		<tr>
			<td>PROLENE Polypropylene Suture 5-0</td>
			<td>Ethicon</td>
			<td>8725H</td>
			<td></td>
		</tr>
		<tr>
			<td>Puralube Opthalmic Ointment</td>
			<td>Perrigo</td>
			<td>574402511</td>
			<td></td>
		</tr>
		<tr>
			<td>Q-tips&#160;</td>
			<td>B.H.W</td>
			<td>271676</td>
			<td></td>
		</tr>
		<tr>
			<td>SomnoSuite Low-Flow Anesthesia System</td>
			<td>Kent Scientific</td>
			<td>SOMNO</td>
			<td></td>
		</tr>
	</tbody>
</table>

simple continuous glucose monitoring in freely moving mice

Mice are a common model organism used to study metabolic diseases such as diabetes mellitus. Glucose levels are typically measured by tail-bleeding, which requires handling the mice, causes stress, and does not provide data on freely behaving mice during the dark cycle. State-of-the-art continuous glucose measurement in mice requires inserting a probe into the aortic arch of the mouse, as well as a specialized telemetry system. This challenging and expensive method has not been adopted by most labs. Here, we present a simple protocol involving the utilization of commercially available continuous glucose monitors used by millions of patients to measure glucose continuously in mice as a part of basic research. The glucose-sensing probe is inserted into the subcutaneous space in the back of the mouse through a small incision to the skin and is held in place tightly using a couple of sutures. The device is sutured to the mouse skin to ensure it remains in place. The device can measure glucose levels for up to 2 weeks and sends the data to a nearby receiver without any need to handle the mice. Scripts for the basic data analysis of glucose levels recorded are provided. This method, from surgery to computational analysis, is cost-effective and potentially very useful in metabolic research.

Surgical outcome 
Results from eight HSD:ICR mice (aged 8 weeks) fed a high-fat high-sucrose diet (HFHS) for 18 weeks and five lean HSD:ICR mice (aged 12 weeks) are shown. The device we used stores data for up to 8 h. Access to the local animal facility was restricted to 07:00-19:00, thus prohibiting data collection during the late P.M. hours, when the mice are active. The mice were, therefore, placed in a room with reverse lighting for 7 days before the surgical procedure, with dark hours between 8...

Watch this Scientific Journal Video about Simple Continuous Glucose Monitoring in Freely Moving Mice at JoVE.com

Simple Continuous Glucose Monitoring in Freely Moving Mice

Here, we describe a simple method to implant a commercial continuous glucose monitor designed for patients onto mice and provide the scripts to analyze the results.

Mice are a common model organism used to study metabolic diseases such as diabetes mellitus. Glucose levels are typically measured by tail-bleeding, which ...

simple-continuous-glucose-monitoring-in-freely-moving-mice

Research

JoVE Journal

Biology

4.8K Views.  The Hebrew University-Hadassah Medical School. Here, we describe a simple method to implant a commercial continuous glucose monitor designed for patients onto mice and provide the scripts to analyze the results.

Video: Simple Continuous Glucose Monitoring in Freely Moving Mice

Pyrosequencing: A Simple Method for Accurate Genotyping

Pharmacogenetic research benefits first-hand from the abundance of information provided by the completion of the Human Genome Project. With such a tremendous amount of data available comes an explosion of genotyping methods. Pyrosequencing(R) is one of the most thorough yet simple methods to date used to analyze polymorphisms. It also has the ability to identify tri-allelic, indels, short-repeat polymorphisms, along with determining allele percentages for methylation or pooled sample assessment. In addition, there is a standardized control sequence that provides internal quality control. This method has led to rapid and efficient single-nucleotide polymorphism evaluation including many clinically relevant polymorphisms. The technique and methodology of Pyrosequencing is explained.


Pyrosequencing(R) is one of the most thorough yet simple methods to date used to analyze polymorphisms. This method has led to rapid and efficient single-nucleotide polymorphism evaluation including many clinically relevant polymorphisms. The technique and methodology of Pyrosequencing is explained.

Pharmacogenetic research benefits first-hand from the abundance of information provided by the completion of the Human Genome Project. With such a ...

Recordings of Neural Circuit Activation in Freely Behaving Animals

The relationship between patterns of neural activity and corresponding behavioral expression is difficult to establish in unrestrained animals. Traditional non-invasive methods require at least partially restrained research subjects, and they only allow identification of large numbers of simultaneously activated neurons. On the other hand, small ensembles of neurons or individual neurons can only be measured using single-cell recordings obtained from largely reduced preparations. Since the expression of natural behavior is limited in restrained and dissected animals, the underlying neural mechanisms that control such behavior are difficult to identify. 
Here, I present a non-invasive physiological technique that allows measuring neural circuit activation in freely behaving animals. Using a pair of wire electrodes inside a water-filled chamber, the bath electrodes record neural and muscular field potentials generated by juvenile crayfish during natural or experimentally evoked escape responses. The primary escape responses of crayfish are mediated by three different types of tail-flips which move the animals away from the point of stimulation. Each type of tail-flip is controlled by its own neural circuit; the two fastest and most powerful escape responses require activation of different sets of large &#8220;command&#8221; neurons. In combination with behavioral observations, the bath electrode recordings allow unambiguous identification of these neurons and the associated neural circuits. Thus activity of neural circuitry underlying naturally occurring behavior can be measured in unrestrained animals and in different behavioral contexts.

Non-invasive measurements of neural activity patterns in freely behaving animals are obtained by combining neurophysiological recordings with high speed videography.

The relationship between patterns of neural activity and corresponding behavioral expression is difficult to establish in unrestrained animals. ...

Measures of Heart and Ventilatory Rates in Freely Moving Crayfish

The fear, flight or fight response serves as the fundamental physiological basis for examining an organism's awareness of its environment under an impending predator attack.  Although it is not known whether invertebrates posses an autonomic nervous system identical to that of vertebrates, evidence shows invertebrates have a  sympathetic-like  response to regulate the internal environment and ready the organism to act behaviorally to a given stimuli.  Furthermore, this physiological response can be feasibly measured and it acts as a biological index for the animal's internal state.  Measurements of the physiological response can be directly related to internal and external stressors through changes in the central nervous system controlled coordination of the cardio-vascular and respiratory systems.   More specifically, monitoring heart and ventilation rates provide quantifiable measures of the stress response not always behaviorally observed. Crayfish are good model organisms for heart and ventilatory rate measurements due to the feasibility of recording, as well as the rich history known of the morphology of the crayfish, dating back to Huxley in 1888, and the well-studied typical behaviors.

Invertebrates show an autonomic sympathetic-like response similar to that described for vertebrates. The coordination of the cardio-vascular and ventilatory systems allows for measurement of a biological index in which to assess an organism internal state.

The fear, flight or fight response serves as the fundamental physiological basis for examining an organism's awareness of its environment under an ...

Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish water and sediment. The choice of biological indicators must be based on reliable scientific knowledge and, possibly, on the availability of standardized procedures. In this article, we present a standardized protocol that used the marine crustacean Artemia to evaluate the toxicity of chemicals and/or of marine environmental matrices. Scientists propose that the brine shrimp (Artemia) is a suitable candidate for the development of a standard bioassay for worldwide utilization. A number of papers have been published on the toxic effects of various chemicals and toxicants on brine shrimp (Artemia). The major advantage of this crustacean for toxicity studies is the overall availability of the dry cysts; these can be immediately used in testing and difficult cultivation is not demanded1,2. Cyst-based toxicity assays are cheap, continuously available, simple and reliable and are thus an important answer to routine needs of toxicity screening, for industrial monitoring requirements or for regulatory purposes3. The proposed method involves the mortality as an endpoint. The numbers of survivors were counted and percentage of deaths were calculated. Larvae were considered dead if they did not exhibit any internal or external movement during several seconds of observation4. This procedure was standardized testing a reference substance (Sodium Dodecyl Sulfate); some results are reported in this work. This article accompanies a video that describes the performance of procedural toxicity testing, showing all the steps related to the protocol.

Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana

This study concerns the development and standardization of a valuable methodological protocol to determine long-term (14 days) lethal toxicity exerted by chemical substances, industrial wastewater or sewage and liquid environmental samples on the saltwater crustacean, Artemia franciscana.

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish ...

Autonomously Bioluminescent Mammalian Cells for Continuous and Real-time Monitoring of Cytotoxicity

Mammalian cell-based in vitro assays have been widely employed as alternatives to animal testing for toxicological studies but have been limited due to the high monetary and time costs of parallel sample preparation that are necessitated due to the destructive nature of firefly luciferase-based screening methods. This video describes the utilization of autonomously bioluminescent mammalian cells, which do not require the destructive addition of a luciferin substrate, as an inexpensive and facile method for monitoring the cytotoxic effects of a compound of interest. Mammalian cells stably expressing the full bacterial bioluminescence (luxCDABEfrp) gene cassette autonomously produce an optical signal that peaks at 490 nm without the addition of an expensive and possibly interfering luciferin substrate, excitation by an external energy source, or destruction of the sample that is traditionally performed during optical imaging procedures. This independence from external stimulation places the burden for maintaining the bioluminescent reaction solely on the cell, meaning that the resultant signal is only detected during active metabolism. This characteristic makes the lux-expressing cell line an excellent candidate for use as a biosentinel against cytotoxic effects because changes in bioluminescent production are indicative of adverse effects on cellular growth and metabolism. Similarly, the autonomous nature and lack of required sample destruction permits repeated imaging of the same sample in real-time throughout the period of toxicant exposure and can be performed across multiple samples using existing imaging equipment in an automated fashion.

Mammalian cells expressing the bacterial bioluminescence gene cassette (lux) produce light autonomously. The resulting bioluminescent dynamics upon chemical exposure have been demonstrated to reflect the treatment effects on cellular growth and metabolism, making these cells an inexpensive, continuous, real-time toxicity screening tool that can easily be adapted for high-throughput automation.

Mammalian  cell-based in vitro assays have been  widely employed as alternatives to animal testing for toxicological studies but  have been limited due to ...

Filtration Isolation of Nucleic Acids:  A Simple and Rapid DNA Extraction Method

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad to extract cellular DNA from whole blood in less than 2 min. The blood specimen is treated with detergent, mixed briefly and applied by pipet to the separation membrane. The lysate wicks into the blotting pad due to capillary action, capturing the genomic DNA on the surface of the separation membrane. The extracted DNA is retained on the membrane during a simple wash step wherein PCR inhibitors are wicked into the absorbent blotting pad. The membrane containing the entrapped DNA is then added to the PCR reaction without further purification. This simple method does not require laboratory equipment and can be easily implemented with inexpensive laboratory supplies. Here we describe a protocol for highly sensitive detection and quantitation of HIV-1 proviral DNA from 100 &#181;l whole blood as a model for early infant diagnosis of HIV that could readily be adapted to other genetic targets.

We describe here a simple and rapid paper-based DNA extraction method of HIV proviral DNA from whole blood detected by quantitative PCR. This protocol can be extended for use in detecting other genetic markers or using alternative amplification methods.

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad ...

A Simple High Efficiency Protocol for Pancreatic Islet Isolation from Mice

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other important biological functions. The islets primarily consist of five types of hormone-secreting cells: &#945; cells secrete glucagon, &#946; cells secrete insulin, &#948; cells secrete somatostatin, &#949; cells secrete ghrelin, and PP cells secrete pancreatic polypeptide. Sixty to 80% of the cells in the islets are &#946; cells, which are the most important cell population to study insulin secretion. Pancreatic islets are a crucial model system to study ex vivo insulin secretion. Acquiring high quality islets is of great importance for diabetes research. Most islet isolation procedures require technically difficult to access site of collagenase injection, harsh and complex digestion procedures, and multiple density gradient purification steps. This paper features a simple high yield mouse islet isolation method with detailed descriptions and realistic demonstrations, showing the following specific steps: 1) injection of collagenase P at the ampulla of Vater, a small area joining the pancreatic duct and the common bile duct, 2) enzymatic digestion and mechanical separation of the exocrine pancreas, and 3) a single gradient purification step. The advantages of this method are the injection of digestive enzyme using the more accessible ampulla of Vater, more complete digestion using combination of enzymatic and mechanical approaches, and a simpler single gradient purification step. This protocol produces approximately 250&#8212;350 islets per mouse; and islets are suitable for various ex vivo studies. Possible caveats of this procedure are potentially damaged islets due to enzymatic digestion and/or prolonged gradient incubation, all of which can be largely avoided by careful ad justification of incubation time.

This islet isolation protocol described a novel route of collagenase injection to digest the exocrine tissue and a simplified gradient procedure to purify the islets from mice. It involves enzymatic digestion, gradient separation/purification, and islet hand-picking. Successful isolation can yield 250&#8211;350 high quality and fully functional islets per mouse.

Pancreatic islets, also called the Islets of Langerhans, are a cluster of endocrine cells which produces hormones for glucose regulation and other ...

A Simple and Efficient Method for In Vivo Cardiac-specific Gene Manipulation by Intramyocardial Injection in Mice

Gene manipulation specifically in the heart significantly potentiate the investigation of cardiac disease pathomechanisms and their therapeutic potential. In vivo cardiac-specific gene delivery is commonly achieved by either systemic or local delivery. Systemic injection via tail vein is easy and efficient in manipulating cardiac gene expression by using recombinant adeno-associated virus 9 (AAV9). However, this method requires a relatively high amount of vector for efficient transduction, and may result in nontarget organ gene transduction. Here, we describe a simple, efficient, and time-saving method of intramyocardial injection for in vivo cardiac-specific gene manipulation in mice. Under anesthesia (without ventilation), the pectoral major and minor muscles were bluntly dissected, and the mouse heart was quickly exposed by manual externalization through a small incision at the fourth intercostal space. Subsequently, adenovirus encoding luciferase (Luc) and vitamin D receptor (VDR), or short hairpin RNA (shRNA) targeting VDR, was injected with a Hamilton syringe into the myocardium. Subsequent in vivo imaging demonstrated that luciferase was successfully overexpressed specifically in the heart. Moreover, Western blot analysis confirmed the successful overexpression or silencing of VDR in the mouse heart. Once mastered, this technique can be used for gene manipulation, as well as injection of cells or other materials such as nanogels in the mouse heart.

A Simple and Efficient Method for In Vivo Cardiac-specific Gene Manipulation by Intramyocardial Injection in Mice

Here we present a protocol for cardiac-specific gene manipulation in mice. Under anesthesia, the mouse hearts were externalized through the fourth intercostal space. Subsequently, adenoviruses encoding specific genes were injected with a syringe into the myocardium, followed by protein expression measurement via in vivo imaging and Western blot analysis.

Gene manipulation specifically in the heart significantly potentiate the investigation of cardiac disease pathomechanisms and their therapeutic potential. ...

Detecting Establishment of Shared Blood Supply in Parabiotic Mice by Caudal Vein Glucose Injection

Parabiosis is an experimental method for surgically combining two parallel animals along the longitudinal axis of the body. We present a protocol for detecting the successful establishment of blood chimerism in parabionts by a caudal vein injection of glucose. Parabiotic mice were constructed. Glucose was injected into the donor mouse through the tail vein, and the fluctuation of blood glucose level was measured in both mice using a blood glucometer at different time points. Our results showed that after glucose injection, the blood glucose level in donor mice increased sharply after 1 min and decreased slowly thereafter. Meanwhile, the blood glucose level of the recipient mice peaked 15 min after injection. Similar results were obtained with Evans blue, used as a positive control for glucose. The synchronous fluctuation of blood glucose levels indicates that blood flow between the two mice was established successfully.

Here we describe a new method of detecting successful establishment of shared blood circulation of two parabionts through a caudal vein injection of glucose, which causes minimal damage and is not fatal to the parabionts.

Parabiosis is an experimental method for surgically combining two parallel animals along the longitudinal axis of the body. We present a protocol for ...

Simple Detection of Primary Cilia by Immunofluorescence

Primary cilia are dynamically regulated during cell cycle progression, specifically during the G0/G1 phases of the cell cycle, being resorbed prior to mitosis. Primary cilia can be visualized with highly sophisticated methods, including transmission electron microscopy, 3D imaging, or using software for the automatic detection of primary cilia. However, immunofluorescent staining of primary cilia is needed to perform these methods. This publication describes a protocol for the easy detection of primary cilia in vitro by staining acetylated alpha tubulin (axoneme) and gamma tubulin (basal body). This immunofluorescent staining protocol is relatively simple and results in high-quality images. The present protocol describes how four cell lines (C2C12, MEF, NHLF, and skin fibroblasts) expressing primary cilia were fixed, immunostained, and imaged with a fluorescent or confocal microscope.

Primary cilia are extracellular structures associated with the centriole. Primary cilia detection by immunofluorescent staining is a relatively simple procedure that results in extremely high-quality images. In this protocol, fibroblasts expressing primary cilia were fixed, immunostained, and imaged in a fluorescent or confocal microscope.

Primary cilia are dynamically regulated during cell cycle progression, specifically during the G0/G1 phases of the cell cycle, being resorbed prior to ...