Name: the use of chemostats in microbial systems biology
Uploaded: 2013-10-14T20:45:00
Description: Watch this Scientific Journal Video about The Use of Chemostats in Microbial Systems Biology at JoVE.com

Dette arbeidet ble støttet av oppstart midler fra New York University. Vi takker Maitreya Dunham og Matt Brauer som opprinnelig utviklet bruken av Sixfors bioreaktorer som chemostats.

Prinsippet for kontinuerlig dyrking ved hjelp av en chemostat kan realiseres i forskjellige implementeringer. I alle chemostats er det viktig å ha en) fremgangsmåter for å opprettholde sterilitet av alle komponenter, 2) en godt blandet kultur, 3) hensiktsmessig lufting av dyrkings-beholderen, og 4) en pålitelig middel for medietilsetning og fjerning av kulturen. Her beskriver vi bruken av en Sixfors bioreaktor (INFORS Inc) som en chemostat ved hjelp av fremgangsmåter som lett kan tilpasses alternative oppsett. ...

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Chemostats muliggjøre dyrking av mikrober i vekstkontrollert steady-state. Cellene vokser kontinuerlig ved en konstant hastighet som resulterer i en invariant ytre miljø. Dette er i motsetning til satsvis kultur metoder hvor det ytre miljø er kontinuerlig skiftende og hastigheten av celleveksten er bestemt av et komplekst samspill mellom omgivelsene og genotype. Således er en stor fordel ved dyrkning av mikroorganismer i chemostats enn satskulturer evnen til eksperimentelt å kontrollere veksten av celler. <p cl...

Veksten av celler reguleres av komplekse nettverk av samspill genetiske og miljømessige faktorer 1,2. Den multifaktoriell regulering av cellevekst nødvendiggjør en system-nivå tilnærming til studien. Imidlertid er den grundige studier med regulert cellevekst utfordret av vanskeligheten med eksperimentelt å styre hastigheten som cellene vokser. Videre, i selv de enkleste eksperimentene ekstracellulære forholdene er ofte dynamisk og kompleks som celler kontinuerlig endre sine omgivelser som de sprer. En løsning på disse problemer er gitt av chemostat: en fremgangsmåte for dyrking av celler som gir eksperimentell kontroll av cellevekstrater i definerte, invariante og kontrollerte omgivelser. Fremgangsmåten for kontinuerlig dyrking ved hjelp av en chemostat ble uavhengig beskrevet av Monod 3 og Novick &amp; Szilárd 4 i 1950. Som opprinnelig tenkt, er celler dyrket i et bestemt volum av media som er conkontinuerlig å fortynnes ved tilsetning av nye medier og samtidig fjerning av gamle mediet og cellene (figur 1). Sammen ordinære differensialligninger (figur 2) beskriver hastigheten av endringen i celletetthet (x), og konsentrasjonen av et vekstbegrensende næringsstoff (er) i chemostat fartøyet. Viktigere, ligningssystemet spår en enkelt (null) stabil steady-state (figur 3) med bemerkelsesverdig implikasjon at ved steady-state, er lik den kursen den spesifikke vekstraten av celler (dvs. den eksponentielle veksten konstant) ved hvilken kulturen fortynnet (D). Ved å variere fortynning satsen er det mulig å etablere steady-state-populasjoner av celler ved forskjellige vekstrater og under forskjellige betingelser av næringsbegrensning. Den eksperimentelle kontroll av vekst ved hjelp chemostats var kritisk til utviklingen av en forståelse av hvordan cellefysiologi endringermed vekstrater 5,6. Men dette tidligere bærebjelke i mikrobiologiske metoder ble stadig mer obskure under eksplosjonen i molekylær biologi forskning i løpet av slutten av det tjuende århundre. I dag, har fornyet interesse i vekst kontroll i både mikrober og flercellede organismer og bruk av metoder genom-skala for systemer-nivå analyse fornyet motivasjon for bruk av chemostats. Her beskriver vi tre programmer som kapitalisere på den presis kontroll av cellevekstrater og det ytre miljø som er unikt mulig hjelp chemostats. Først beskriver vi bruk av chemostats å undersøke hvordan den overflod av tusenvis av biomolekyler - for eksempel utskrifter og metabolitter - er coordinately regulert med veksten. For det andre, vil vi beskrive hvordan chemostats kan brukes for å oppnå nøyaktige beregninger av vekst-rate forskjeller mellom forskjellige genotyper i næringsstoff-begrensede miljøer ved hjelp av konkurranseeksperimenter. Tredje, vi beskrive hvordan chemostats kanbli brukt for å studere utviklingen av adaptive celler som vokser i faste næringsfattige omgivelser. Disse eksemplene er eksempler på hvilke måter chemostats er slik at systemene nivå undersøkelser av cellevekst regulering, genet miljø samspill og adaptiv evolusjon.

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments (optional)</td>
		</tr>
		<tr>
			<td>Infors-HT Sixfors Chemostat</td>
			<td>Appropriate Technical Resources, Inc.</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Glass Bottle 9.5 L</td>
			<td>Fisher Scientific</td>
			<td>02-887-1</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Pinchcock</td>
			<td>Fisher Scientific</td>
			<td>05-867</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Stopper, Size 12, Green Neoprene</td>
			<td>Cole-Palmer</td>
			<td>EW-62991-42</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Straight Connector</td>
			<td>Cole-Palmer</td>
			<td>EW-30703-02</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>General purpose ties 4 in</td>
			<td>Fisher Scientific</td>
			<td>NC9557052</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Tubing, Silicone Rubber</td>
			<td>Small Parts</td>
			<td>B000FMWTDE</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Tubing, Silicone, 3/8 in OD</td>
			<td>Fisher Scientific</td>
			<td>02-587-1Q</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Tubing, Silicone, 7/32 in OD</td>
			<td>Fisher Scientific</td>
			<td>02-587-1E</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Tubing, Stainless Steel, 3/16 in OD</td>
			<td>McMaster-Carr</td>
			<td>6100K164</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Tubing, Stainless Steel, 3/8 in OD</td>
			<td>McMaster-Carr</td>
			<td>6100K161</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Hook Connectors</td>
			<td>Fisher Scientific</td>
			<td>14-66-18Q</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Ratchet Clamp</td>
			<td>Cole-Palmer</td>
			<td>EW-06403-11</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Luer, Female</td>
			<td>Cole-Palmer</td>
			<td>EW-45512-34</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Luer, Male</td>
			<td>Cole-Palmer</td>
			<td>EW-45513-04</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Millipore Aervent MTGR05010 62 mm Filter, 0.2 &mu;m</td>
			<td>Fisher Scientific</td>
			<td>MTGR05010</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>PTFE Acrodisc CR 13 mm filters, 0.2 &mu;m</td>
			<td>Fisher Scientific</td>
			<td>NC9131037</td>
			<td>For Media Vessel and Hosing</td>
		</tr>
		<tr>
			<td>Direct-Reading Flowtube for Air</td>
			<td>Cole-Palmer</td>
			<td>EW-32047-77</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Direct-Reading Flowtube for Nitrogen</td>
			<td>Cole-Palmer</td>
			<td>EW-32048-63</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Gas Proportioner Multitube Frames</td>
			<td>Cole-Palmer</td>
			<td>EW-03218-50</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Regulator, Two-Stage Analytical</td>
			<td>Airgas</td>
			<td>Y12-N145D580</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Hose Adaptor, Stainless Steel</td>
			<td>Airgas</td>
			<td>Y99-26450</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Hose Male Adaptor</td>
			<td>Airgas</td>
			<td>WES544</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Norprene Tubing</td>
			<td>US Plastics</td>
			<td>57280</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Tripod Base</td>
			<td>Cole-Palmer</td>
			<td>EW-03218-58</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Valve Cartridges</td>
			<td>Cole-Palmer</td>
			<td>EW-03217-92</td>
			<td>For Nitrogen Gas Setup</td>
		</tr>
		<tr>
			<td>Carboy 10 L</td>
			<td>Fisher Scientific</td>
			<td>02-963-2A</td>
			<td>For Media Preperation</td>
		</tr>
		<tr>
			<td>Steritop Sterile Vacuum Bottle-Top Filters, 1,000 ml, PES membrane; for 45 mm neck size</td>
			<td>Fisher Scientific</td>
			<td>SCGP-T10-RE</td>
			<td>For Media Preperation</td>
		</tr>
		<tr>
			<td>Media Bottle 100 ml, 45 mm neck size</td>
			<td>Fisher Scientific</td>
			<td>FB-800-100</td>
			<td>For Media Preperation</td>
		</tr>
		<tr>
			<td>calcium chloride&middot;2H2O</td>
			<td>Fisher Scientific</td>
			<td>C79-500</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>sodium chloride</td>
			<td>Fisher Scientific</td>
			<td>BP358-1</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>magnesium sulfate&middot;7H2O</td>
			<td>Sigma Aldrich</td>
			<td>230391</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>potassium phosphate monobasic</td>
			<td>Fisher Scientific</td>
			<td>AC424205000</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>ammonium sulfate</td>
			<td>Fisher Scientific</td>
			<td>AC423400010</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>potassium chloride</td>
			<td>Sigma Aldrich</td>
			<td>P9541</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>boric acid</td>
			<td>Sigma Aldrich</td>
			<td>B6768</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>copper sulfate&middot;5H2O</td>
			<td>Sigma Aldrich</td>
			<td>209198</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>potassium iodide</td>
			<td>Sigma Aldrich</td>
			<td>60400</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>ferric chloride&middot;6H2O</td>
			<td>Fisher Scientific</td>
			<td>I88-100</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>manganese sulfate&middot;H2O</td>
			<td>Sigma Aldrich</td>
			<td>230391</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>sodium molybdate&middot;2H2O</td>
			<td>Sigma Aldrich</td>
			<td>M7634</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>zinc sulfate&middot;7H2O</td>
			<td>Fisher Scientific</td>
			<td>Z68-500</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>biotin</td>
			<td>Fisher Scientific</td>
			<td>BP232-1</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>calcium pantothenate</td>
			<td>Fisher Scientific</td>
			<td>AC24330-1000</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>folic acid</td>
			<td>Sigma Aldrich</td>
			<td>F7876</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>inositol (aka myo-inositol)</td>
			<td>Fisher Scientific</td>
			<td>AC12226-1000</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>niacin (aka nicotinic acid)</td>
			<td>Sigma Aldrich</td>
			<td>N4126</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>p-aminobenzoic acid</td>
			<td>Fisher Scientific</td>
			<td>AC14621-2500</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>pyridoxine HCl</td>
			<td>Sigma Aldrich</td>
			<td>P9755</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>riboflavin</td>
			<td>Sigma Aldrich</td>
			<td>R4500-25G</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>thiamine HCl</td>
			<td>Fisher Scientific</td>
			<td>BP892-100</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>Leucine</td>
			<td>Sigma Aldrich</td>
			<td>L8000-100G</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>Uracil</td>
			<td>Sigma Aldrich</td>
			<td>U0750</td>
			<td>Media Reagents</td>
		</tr>
		<tr>
			<td>Dextrose</td>
			<td>Fisher Scientific</td>
			<td>DF0155-08-5</td>
			<td>Media Reagents</td>
		</tr>
	</tbody>
</table>

the use of chemostats in microbial systems biology

Celler regulere veksten i respons til signaler fra den ytre verden. Som cellen vokser, må ulike cellulære prosesser koordineres inkludert makromolekylært syntese, metabolisme og til slutt, engasjement for celledeling syklus. Den chemostat, en metode for eksperimentelt kontrollerende celle vekst, gir et kraftig middel til systematisk å studere hvordan vekstraten påvirker cellulære prosesser - inkludert genuttrykk og metabolisme - og de regulatoriske nettverk som styrer frekvensen av cellevekst. Ved opprettholdt i hundrevis av generasjoner chemostats kan brukes til å studere adaptive utviklingen av mikroorganismer i miljøforhold som begrenser cellevekst. Vi beskriver prinsippet om chemostat kulturer, vise sin drift og gi eksempler på sine ulike programmer. Etter en periode med stillstand etter at de ble introdusert i midten av det tjuende århundre, konvergens av genom-skala metoder med en fornyet iterest i regulering av cellevekst og det molekylære grunnlaget for adaptiv evolusjon er stimulerende en renessanse i bruk av chemostats i biologisk forskning.

En stor fordel med chemostats er evnen til å kontrollere veksten av celler eksperimentelt ved å variere fortynningshastigheten. I det spirende gjær, Saccharomyces cerevisiae, morfologi av en celle er informativ av sin fase i celledeling syklus. Populasjoner med høyere vekstrater inneholder en høyere andel av aktivt delende celler som bestemt ved å måle hvor stor del av unbudded celler (figur 5A). Analyser av global mRNA ekspresjon i chemostat kulturer har vist at ekspresjonen av mange gener som e...

Watch this Scientific Journal Video about The Use of Chemostats in Microbial Systems Biology at JoVE.com

The Use of Chemostats in Microbial Systems Biology

Cellevekstraten er en regulert prosess og en primær determinant av cellefysiologi. Kontinuerlig dyrking ved hjelp chemostats muliggjør ytre kontroll av celleveksthastighet av næringsbegrensning å lette studiet av molekylære nettverk som kontrollerer cellevekst, og hvor disse nettverkene utvikles for å optimalisere cellevekst.

Bruk av Chemostats i Microbial Systems Biology

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated ...

the-use-of-chemostats-in-microbial-systems-biology

Research

JoVE Journal

Biology

Investigating the Microbial Community in the Termite Hindgut - Interview

Jared Leadbetter explains why the termite-gut microbial community is an excellent system for studying the complex interactions between microbes.     The symbiotic relationship existing between the host insect and lignocellulose-degrading gut microbes is explained, as well as the industrial uses of these microbes for degrading plant biomass and generating biofuels.

Jared Leadbetter explains why the termite-gut microbial community is an excellent system for studying the complex interactions between microbes. The symbiotic relationship existing between the host insect and lignocellulose-degrading gut microbes is explained, as well as the industrial uses of these microbes for degrading plant biomass and generating biofuels.

Jared Leadbetter explains why the termite-gut microbial community is an excellent system for studying the complex interactions between microbes.     The ...

Microbial Communities in Nature and Laboratory - Interview

Biology of Microbial Communities  - Interview

Using Micro-Electro-Mechanical Systems (MEMS) to Develop Diagnostic Tools

Using Micro-Electro-Mechanical Systems MEMS to Develop Diagnostic Tools

The use of Biofeedback in Clinical Virtual Reality: The INTREPID Project

Generalized anxiety disorder (GAD) is a psychiatric disorder characterized by a constant and unspecific anxiety that interferes with daily-life activities. Its high prevalence in general population and the severe limitations it causes, point out the necessity to find new efficient strategies to treat it. Together with the cognitive-behavioral treatments, relaxation represents a useful approach for the treatment of GAD, but it has the limitation that it is hard to be learned. The INTREPID project is aimed to implement a new instrument to treat anxiety-related disorders and to test its clinical efficacy in reducing anxiety-related symptoms. The innovation of this approach is the combination of virtual reality and biofeedback, so that the first one is directly modified by the output of the second one. In this way, the patient is made aware of his or her reactions through the modification of some features of the VR environment in real time. Using mental exercises the patient learns to control these physiological parameters and using the feedback provided by the virtual environment is able to gauge his or her success. The supplemental use of portable devices, such as PDA or smart-phones, allows the patient to perform at home, individually and autonomously, the same exercises experienced in therapist's office. The goal is to anchor the learned protocol in a real life context, so enhancing the patients' ability to deal with their symptoms. The expected result is a better and faster learning of relaxation techniques, and thus an increased effectiveness of the treatment if compared with traditional clinical protocols.

The Project on Virtual Reality Intelligent Multi-sensor System for the Treatment of Anxiety-related Disorders (INTREPID) is aimed at developing a multi-sensor context-aware virtual reality system for the treatment of anxiety-related disorders.

Generalized anxiety disorder (GAD) is a psychiatric disorder characterized by a constant and unspecific anxiety that interferes with daily-life ...

Window on a Microworld: Simple Microfluidic Systems for Studying Microbial Transport in Porous Media

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in the environment, as well as directly for the transmission of pathogens to drinking water supplies. Natural porous media is composed of an intricate physical topology, varied surface chemistries, dynamic gradients of nutrients and electron acceptors, and a patchy distribution of microbes. These features vary substantially over a length scale of microns, making the results of macro-scale investigations of microbial transport difficult to interpret, and the validation of mechanistic models challenging. Here we demonstrate how simple microfluidic devices can be used to visualize microbial interactions with micro-structured habitats, to identify key processes influencing the observed phenomena, and to systematically validate predictive models. Simple, easy-to-use flow cells were constructed out of the transparent, biocompatible and oxygen-permeable material poly(dimethyl siloxane). Standard methods of photolithography were used to make micro-structured masters, and replica molding was used to cast micro-structured flow cells from the masters. The physical design of the flow cell chamber is adaptable to the experimental requirements: microchannels can vary from simple linear connections to complex topologies with feature sizes as small as 2 &mu;m. Our modular EcoChip flow cell array features dozens of identical chambers and flow control by a gravity-driven flow module. We demonstrate that through use of EcoChip devices, physical structures and pressure heads can be held constant or varied systematically while the influence of surface chemistry, fluid properties, or the characteristics of the microbial population is investigated. Through transport experiments using a non-pathogenic, green fluorescent protein-expressing Vibrio bacterial strain, we illustrate the importance of habitat structure, flow conditions, and inoculums size on fundamental transport phenomena, and with real-time particle-scale observations, demonstrate that microfluidics offer a compelling view of a hidden world.

Microfluidic devices can be used to visualize complex natural processes in real time and at the appropriate physical scales. We have developed a simple microfluidic device that mimics key features of natural porous media for studying growth and transport of bacteria in the subsurface.

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in ...

Determining the Contribution of the Energy Systems During Exercise

One of the most important aspects of the metabolic demand is the relative contribution of the energy systems to the total energy required for a given physical activity. Although some sports are relatively easy to be reproduced in a laboratory (e.g., running and cycling), a number of sports are much more difficult to be reproduced and studied in controlled situations. This method presents how to assess the differential contribution of the energy systems in sports that are difficult to mimic in controlled laboratory conditions. The concepts shown here can be adapted to virtually any sport.
The following physiologic variables will be needed: rest oxygen consumption, exercise oxygen consumption, post-exercise oxygen consumption, rest plasma lactate concentration and post-exercise plasma peak lactate. To calculate the contribution of the aerobic metabolism, you will need the oxygen consumption at rest and during the exercise. By using the trapezoidal method, calculate the area under the curve of oxygen consumption during exercise, subtracting the area corresponding to the rest oxygen consumption. To calculate the contribution of the alactic anaerobic metabolism, the post-exercise oxygen consumption curve has to be adjusted to a mono or a bi-exponential model (chosen by the one that best fits). Then, use the terms of the fitted equation to calculate anaerobic alactic metabolism, as follows: ATP-CP metabolism = A1 (mL . s-1) x t1 (s). Finally, to calculate the contribution of the lactic anaerobic system, multiply peak plasma lactate by 3 and by the athlete&#x2019;s body mass (the result in mL is then converted to L and into kJ).
The method can be used for both continuous and intermittent exercise. This is a very interesting approach as it can be adapted to exercises and sports that are difficult to be mimicked in controlled environments. Also, this is the only available method capable of distinguishing the contribution of three different energy systems. Thus, the method allows the study of sports with great similarity to real situations, providing desirable ecological validity to the study.

This protocol allows researchers focused on exercise and sports sciences to determine the relative contribution of three different energy systems to the total energy expenditure during a large variety of exercises.

Bestemme Bidrag av energisystemene under trening

One of the most important aspects of the metabolic demand is the relative contribution of the energy systems to the total energy required for a given ...

Linking Predation Risk, Herbivore Physiological Stress and Microbial Decomposition of Plant Litter

The quantity and quality of detritus entering the soil determines the rate of decomposition by microbial communities as well as recycle rates of nitrogen (N) and carbon (C) sequestration1,2. Plant litter comprises the majority of detritus3, and so it is assumed that decomposition is only marginally influenced by biomass inputs from animals such as herbivores and carnivores4,5. However, carnivores may influence microbial decomposition of plant litter via a chain of interactions in which predation risk alters the physiology of their herbivore prey that in turn alters soil microbial functioning when the herbivore carcasses are decomposed6. A physiological stress response by herbivores to the risk of predation can change the C:N elemental composition of herbivore biomass7,8,9 because stress from predation risk increases herbivore basal energy demands that in nutrient-limited systems forces herbivores to shift their consumption from N-rich resources to support growth and reproduction to C-rich carbohydrate resources to support heightened metabolism6. Herbivores have limited ability to store excess nutrients, so stressed herbivores excrete N as they increase carbohydrate-C consumption7. Ultimately, prey stressed by predation risk increase their body C:N ratio7,10, making them poorer quality resources for the soil microbial pool likely due to lower availability of labile N for microbial enzyme production6. Thus, decomposition of carcasses of stressed herbivores has a priming effect on the functioning of microbial communities that decreases subsequent ability to of microbes to decompose plant litter6,10,11.
We present the methodology to evaluate linkages between predation risk and litter decomposition by soil microbes. We describe how to: induce stress in herbivores from predation risk; measure those stress responses, and measure the consequences on microbial decomposition. We use insights from a model grassland ecosystem comprising the hunting spider predator (Pisuarina mira), a dominant grasshopper herbivore (Melanoplus femurrubrum),and a variety of grass and forb plants9.

We present methods to evaluate how predation risk can alter the chemical quality of herbivore prey by inducing dietary changes to meet demands of heightened stress, and how the decomposition of carcasses from these stressed herbivores slows subsequent plant litter decomposition by soil microbes.

Linking predasjonsrisiko, Herbivore fysiologisk stress og mikrobiell nedbryting av Plant Kull

The quantity and quality of detritus entering the soil  determines the rate of decomposition by microbial communities as well as  recycle rates of ...

Design and Analysis of Temperature Preference Behavior and its Circadian Rhythm in Drosophila

The circadian clock regulates many aspects of life, including sleep, locomotor activity, and body temperature (BTR) rhythms1,2. We recently identified a novel Drosophila circadian output, called the temperature preference rhythm (TPR), in which the preferred temperature in flies rises during the day and falls during the night 3. Surprisingly, the TPR and locomotor activity are controlled through distinct circadian neurons3. Drosophila locomotor activity is a well&#160;known circadian behavioral output and has provided strong contributions to the discovery of many conserved mammalian circadian clock genes and mechanisms4. Therefore, understanding TPR will lead to the identification of hitherto unknown molecular and cellular circadian mechanisms. Here, we describe how to perform and analyze the TPR assay. This technique not only allows for dissecting the molecular and neural mechanisms of TPR, but also provides new insights into the fundamental mechanisms of the brain functions that integrate different environmental signals and regulate animal behaviors. Furthermore, our recently published data suggest that the fly TPR shares features with the mammalian BTR3. Drosophila are ectotherms, in which the body temperature is typically behaviorally regulated. Therefore, TPR is a strategy used to generate a rhythmic body temperature in these flies5-8. We believe that further exploration of Drosophila TPR will facilitate the characterization of the mechanisms underlying body temperature control in animals.

Design and Analysis of Temperature Preference Behavior and its Circadian Rhythm in Drosophila

We recently identified a novel Drosophila circadian output, temperature preference rhythm (TPR), in which the preferred temperature in flies rises during the day and falls during the night. TPR is regulated independently from another circadian output, locomotor activity. Here&#160;we describe the design and analysis of TPR in Drosophila.

Design og analyse av temperaturpreferanseatferd og dens døgnrytme i Drosophila

The circadian clock regulates many aspects of life, including sleep, locomotor activity, and body temperature (BTR) rhythms1,2. We recently identified a ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Måle Stivhet<em&gt; Ex Vivo</em&gt; Mus Aorta Bruke Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...