Si ringrazia Melinda Forseth per scattare foto di ostriche e misurando la loro larghezza di gape in ImageJ. Ringraziamo Denise Breitburg per l'accesso per gli acquari con diel ciclismo ipossia e condizioni di pH ciclica. Si ringrazia il centro di ricerca ambientale Smithsonian, Edgewater, Maryland, per lo spazio per gli esperimenti. Gli esperimenti di ipossia sono stati finanziati da un National Oceanic and Atmospheric Administration - Center per sponsorizzato Coastal Ocean Research grant No. NA10NOS4780138 e il fondo di Hunterdon Smithsonian a Denise Breitburg. La valvola gape misurazioni durante l'ipossia esperimenti erano finanziati da una sovvenzione di potenziamento di facoltà di Washington College di Elka T. Porter.

Non abbiamo niente di divulgare.

Focus tipici studi su continuo, estesi periodi di condizioni di bassa dell'ossigeno e la risposta, spesso misurata come la sopravvivenza, degli animali. Tuttavia, allo stato attuale, la nostra comprensione delle risposte comportamentali degli animali all'ipossia diel-ciclismo è minimo63. Quindi, ulteriori studi dovrebbero concentrarsi sul comportamento degli organismi in risposta all'ipossia diel-escursioni in bicicletta, che si verifica regolarmente durante l'estate in molti estuari<sup class="x...

Ipossia, cioè, dissolto le concentrazioni ossigeno [] sufficientemente basso per influenzare negativamente biologico e processi ecologici ma spesso funzionalmente definita come [DO] < 2 mg / L1e anossia (funzionalmente definita come [DO] 0,0-0,2 mg/L) si verificano più frequentemente e gravemente in acque costiere del mondo, estuari e il profondo oceano2,3 e sono spesso aggravate dalla crescente eutrofizzazione4,5. Con un crescente estensione areale di ipossia e anossia, macrofauna sono influenzati negativamente e perdere la misura di habitat e qualità dell'habitat. Il cambiamento climatico è preveduto per peggiorare l'ipossia e anossia6.
In molti estuari stratificati, arricchita di sostanze nutritive come la Chesapeake Bay, Stati Uniti d'America, stagionalmente persistente ipossia può prevalere e può verificarsi anno dopo anno2. Inoltre, diel-ciclismo di ipossia è frequente negli estuari come la baia di Chesapeake e altri luoghi e si verifica tardi durante la notte o le prime ore del mattino in estate7,8.
Maggior parte degli studi si sono concentrati sull'effetto dell'esposizione continua di organismi a bassa [DO] e sulla loro tolleranza all'ipossia e anossia9,10,11,12,13,14 . Inoltre, gli studi hanno esaminato il cambiamento su larga scala nella composizione delle distribuzioni, abbondanze e specie specie in risposta a estesa [DO] basso4,15. Spesso specie che sono molto sensibili a bassa [], morire nelle masse,16 spostando le restanti specie di una fauna più giovane, più piccolo di dimensioni, di breve durata come, ad esempio, trovate sulla mensola Louisiana-Texas ecosistema4.
Cambiamenti comportamentali in genere precedono comunità crollo17 e gli studi hanno riferito sulle risposte comportamentali degli organismi a estesa basso [DO]4,16,17,18,19 ,20,21,22,23,24,25. Questi studi, tuttavia, non si concentrano sulle risposte degli organismi alle esposizioni diel-ciclismo di ipossia e la natura fluttuante di [DO] disponibilità negli estuari.
Diel-ciclismo ipossia negli estuari superficiali ha ricevuto crescente consapevolezza come studi monitorare [DO] più frequentemente nel corso dei giorni con sonde in estuari16,26. Acqua può rimanere ipossica per ore alla fine della notte o le prime ore del mattino in estate quando non c'è nessuna fotosintesi di generazione di ossigeno durante la notte, ma che consumano ossigeno alta respirazione aerobica7,16. Si è inoltre constatato che le maree influenzato il diel ciclismo condizioni basso con più estremi minimi osservati quando bassa marea ha coinciso con la fine della notte27. Solo dopo diverse ore di ipossia [DO] tornare a normoxia7,16,28 nel ciclo giornaliero.
Per determinare la risposta comportamentale di c. virginica diel-ciclismo ipossia e pH abbiamo monitorato l'apertura e la chiusura delle valvole di ostriche esposte al laboratorio indotto diel ciclica e ciclismo di [DO] pH. Gape risposte di bivalvi sono state utilizzate per rilevare condizioni ambientali avverse. Chiusure di valvola di molluschi bivalvi in risposta a contaminanti29,30,31, alghe tossiche32,33,34, l'inquinamento termico35,36 , 37,38,39,40, alimentazione regime39,41, emersione37,42, fotoperiodo43 diminuire la quantità di cibo , 44, pH45,46e combinato pH e ossigeno disciolto47 sono stati misurati. Gape tecniche hanno, ad esempio, incluso osservazioni dirette48,49,13, misurazioni continue utilizzando interruttori reed e magneti (Dreissena monitor)50o sensori in fibra ottica 51 che richiedono acqua limpida. Inoltre, sensori di Hall forza magneti e campi magnetici sono stati utilizzati per studiare la cozza gape angolo52,53,54,55e un sistema di induzione elettromagnetica ad alta frequenza che può misurare la distanza varia tra due bobine elettriche che sono incollati sulle valvole è stato utilizzato56,57,58,59. Una sorgente di alta tensione è necessaria per il sistema di induzione elettromagnetica e potenza deve essere consegnato ad entrambi i lati del guscio52. Questo sistema è anche disponibile nel commercio come il "MOSSELMONITOR" (http://mosselmonitor.nl/).
Un budget di ricerca stretto, abbiamo costruito un monitor economico strain-gauge (SGM) per misurare continuamente gape ostrica sopra indotta da laboratorio diel ciclismo di [DO] e pH, in condizioni di scarsa visibilità. Il nostro sistema è anche molto più semplice rispetto ai sistemi concorrenti, consentendo molti animali da instrumentare durante un esperimento. Abbiamo voluto determinare le risposte comportamentali di c. virginica diel ciclismo grave ([] = 0,6 mg/L) ipossia con pH di controllo (pH = 7.8) e ciclismo pH (pH = 7,8-7.0), rispettivamente e le risposte di gape al delicato ([] = 1,7 mg/L) ipossia. Inoltre, abbiamo voluto determinare se le ostriche sono in grado di rispondere rapidamente ai cambiamenti in [] sopra il diel ciclo e come reagire quando normoxia ritorna dopo un evento hypoxic. Forse le ostriche sono adattate all'ambiente rapidamente fluttuante che si trova in molti estuari16,27 dove vivono. Mentre più complessa valvola gape monitor sono disponibili, la SGM offre una tecnica poco costoso che consente misurazioni continue della valvola gape nelle acque anche in condizioni di scarsa visibilità.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57404/57404fig1.jpg"> Figura 1. Ponte di Wheatstone per l'apparecchiatura di gape valvola. <a href="/files/ftp_upload/57404/57404fig1large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</a>
I sensori dell'estensimetro utilizzati per il monitoraggio gape bivalvi sono film resistivo in un modello di meandro su un supporto di polyimide. Piccole quantità di sforzo modulano la resistenza del sensore. I bivalvi si flette l'estensimetro quando esso gapes causando un cambiamento nella resistenza del sensore. Abbiamo impiegato un ponte di Wheatstone Annulla, equilibrato, per ogni canale bivalvi come mostrato nella Figura 1 per misurare la variazione nella resistenza del sensore. Il ponte di Wheatstone è annullato dal potenziometro che permette un guadagno abbastanza alto essere impiegato dal datalogger. Un ponte di Wheatstone è un metodo standard per misurare con precisione una resistenza sconosciuta utilizzando un rapporto di un noto standard di resistenza e un voltmetro. La storia di questa antichissima tecnica è discussa in Ekelof (2001)60. Abbiamo integrato 12 canali, ognuno con il proprio ponte di Wheatstone e Annulla potenziometro, Strain Gauge Monitor (SGM).

<table><tbody><tr><td>Campbell CR 10x data logger</td><td>Campbell Scientific, Logan, Utah</td><td></td><td>Or other data logger. At Campbell the CR 10X has been replaced with the CR 1000</td></tr><tr><td>Campbell CR 10x multiplexer</td><td>Campbell Scientific, Logan, Utah</td><td></td><td>Data logger needs to have space for 12 channels</td></tr><tr><td>Dsub connector male crimp pins</td><td>TE Connectivity</td><td>205089-1</td><td>pins for gape sensor leads</td></tr><tr><td>PCA tape</td><td>Micro Measurements Corp, NC</td><td></td><td>To seal the strain gauge</td></tr><tr><td>Duro Quick Gel</td><td>Ace Hardware</td><td></td><td>Superglue</td></tr><tr><td>SG13/1000-LY43 or LY41</td><td>Omega Engineering Inc., Stanford, CT</td><td></td><td>Strain gauges</td></tr><tr><td>32 AWG (7/40) teflon Alpha wires</td><td>AlphaWire, Elizabeth, NJ</td><td>2840/7</td><td>Sensor cables, different colors are available</td></tr><tr><td>1/16&quot; heat shrink tubing</td><td>Qualtek</td><td>B01A3QKKO6</td><td>To seal the leads of the sensor cable</td></tr><tr><td>Weller WES51 Analog Soldering Station</td><td>Amazon</td><td></td><td>Lots of soldering, need a good soldering iron. https://www.amazon.com/Weller-WES51-Analog-Soldering-Station/dp/B000BRC2XU/ref=sr_1_23?s=hi&amp;amp;ie=UTF8&amp;amp;qid=1505654295&lt;br/&gt; &amp;amp;sr=1-23&amp;amp;keywords=soldering+iron</td></tr><tr><td>Rosin Soldering Flux Paste</td><td>Amazon</td><td></td><td>Needed for soldering</td></tr><tr><td>60-40 Tin Lead Rosin Core Solder Wire</td><td>Amazon</td><td></td><td>Needed for soldering</td></tr><tr><td>Aquarium sealant</td><td>Home Depot</td><td></td><td>Attach sensors to bivalve</td></tr><tr><td>PC Laptop</td><td></td><td></td><td>Any old PC to run Campbell gape program</td></tr><tr><td>heat gun</td><td>Amazon</td><td></td><td>shrink shrink tubing</td></tr><tr><td>Drill</td><td>Hardware store, Amazon</td><td></td><td>for twisting wires to make sensor cables</td></tr><tr><td>AC to DC power module</td><td>Acopian</td><td>DB15-30</td><td>Wheatstone bridge power supply</td></tr><tr><td>Poteniometer</td><td>Clarostat</td><td>733A</td><td>Wheatsone bridge nulling</td></tr><tr><td>isolating BNC connector</td><td>Sterren Electronics</td><td>&quot;200-148</td><td>Wheatstone bridge output for multimeter</td></tr><tr><td>Fused AC receptical panel module</td><td>Adam technologies</td><td>IEC-GS-1-200</td><td>Wheatstone bridge power supply connector</td></tr><tr><td>976 ohm 1% resistor</td><td>Vishay Dale</td><td>CMF50976R00FHEB</td><td>Wheatstone bridge resistor</td></tr><tr><td>1 kohm 1% resistor</td><td>Vishay Dale</td><td>CMF501K0000FHEB</td><td>Wheatstone bridge resistor</td></tr><tr><td>Potentiometer scale dial</td><td>Kilo International</td><td>462</td><td>10 turn dial for nulling potentiometer</td></tr><tr><td>DB25 male panel connector</td><td>TE connectivity</td><td>1757819-8</td><td>Data logger connector on Wheatstone bridge</td></tr><tr><td>DB25 female panel connector</td><td>TE connectivity</td><td>1757819-8</td><td>Sensor connector to Wheatstone bridge</td></tr><tr><td>perforated circuit board</td><td>Vector electronics</td><td>64P44WE</td><td>circuit board for mounting of bridge components</td></tr><tr><td>enclosure</td><td>Hammond Manufacturing</td><td>1444-29</td><td>Enclosure for sensor readout electronics</td></tr></tbody></table>

a strain gauge monitor (sgm) for continuous valve gape measurements in bivalve molluscs in response to laboratory induced diel-cycling hypoxia and ph

Un monitor di gape valvola poco costoso, basato sul laboratorio, strain-gauge (SGM) è stato sviluppato per monitorare il comportamento di gape valvola di molluschi bivalvi in risposta all'ipossia diel-escursioni in bicicletta. Un ponte di Wheatstone era collegato ad estensimetri che sono stati attaccati ai gusci di ostriche (Crassostrea virginica). I segnali registrati consentito per l'apertura e la chiusura dei bivalvi da registrare continuamente sopra due giorni periodi di ipossia di diel-ciclismo sperimentalmente indotta e diel-ciclismo variazioni di pH. Qui, descriviamo un protocollo per lo sviluppo di un monitor economico strain-gauge e descrivere, in un esperimento di laboratorio di esempio, come abbiamo usato per misurare il comportamento di gape valvola di orientale ostriche (c. virginica), in risposta all'ipossia diel-ciclismo e cicliche variazioni di pH. Gape valvola è stata misurata su ostriche sottoposte a ciclica severa ipossia (0,6 mg/L) dissolto condizioni di ossigeno con e senza cambiamenti ciclici in pH, condizioni cicliche mite hypoxic (1,7 mg/L) e condizioni di normossia (7,3 mg/L). Dimostriamo che quando ostriche incontrano diel ripetuti cicli, rapidamente chiudere loro gusci in risposta all'ipossia severa e chiudere con un ritardo lieve ipossia. Quando viene ripristinato il normoxia, hanno rapidamente aperto nuovamente. Le ostriche non hanno risposto alla condizioni di pH ciclica sovrapposte diel ciclismo ipossia severa. Alle condizioni di ridotta di ossigeno, più di un terzo delle ostriche chiusi contemporaneamente. Dimostriamo che ostriche rispondono all'ipossia diel-escursioni in bicicletta, che deve essere considerato quando valutare il comportamento di bivalvi di ossigeno disciolto. La valvola SGM può essere utilizzata per valutare le risposte dei molluschi bivalvi ai cambiamenti di ossigeno disciolto o contaminanti. Tecniche per migliore guarnizione di tenuta valvola gape estensimetri da acqua di mare hanno bisogno di ulteriore miglioramento per aumentare la longevità dei sensori.

Ostriche esposte all'acqua di estuario normoxic ininterrotta (senza ipossia durante la fase di plateau basso del ciclo giornaliero) sono stati aperte la maggior parte del tempo e soltanto brevemente chiuso raramente (Figura 5). Quando hanno chiuso varia da ostrica di ostrica. Questo modello è stato trovato anche da Loosanoff e Nomejko 194644 e Higgins 198039. Ostriche, inoltre, non hanno risposto alla differenz...

Watch this Scientific Journal Video about A Strain Gauge Monitor SGM for Continuous Valve Gape Measurements in Bivalve Molluscs in Response to Laboratory Induced Diel-cycling Hypoxia and pH at JoVE.co

A Strain Gauge Monitor SGM for Continuous Valve Gape Measurements in Bivalve Molluscs in Response to Laboratory Induced Diel-cycling Hypoxia and pH

Un Monitor di Strain Gauge (SGM) per misurazioni continue di Gape valvola nei molluschi bivalvi in risposta all'ipossia laboratorio indotto Diel-ciclismo e pH

Comprendere le risposte comportamentali di bivalvi sospensione-alimentatori alle variabili ambientali, come l'ossigeno disciolto, può spiegare alcuni processi dell'ecosistema. Abbiamo sviluppato un monitor economico, basato sul laboratorio, strain-gauge (SGM) per misurare le risposte di gape valvola di ostriche, Crassostrea virginica, ipossia diel-ciclismo e pH ciclica.

An inexpensive, laboratory-based, strain gauge valve gape monitor (SGM) was developed to monitor the valve gape behavior of bivalve molluscs in response ...

a-strain-gauge-monitor-sgm-for-continuous-valve-gape-measurements

Research

JoVE Journal

Environment

A Strain Gauge Monitor (SGM) for Continuous Valve Gape Measurements in Bivalve Molluscs in Response to Laboratory Induced Diel-cycling Hypoxia and pH

8.9K Views.  University of Baltimore. Comprendere le risposte comportamentali di bivalvi sospensione-alimentatori alle variabili ambientali, come l'ossigeno disciolto, può spiegare alcuni processi dell'ecosistema. Abbiamo sviluppato un monitor economico, basato sul laboratorio, strain-gauge (SGM) per misurare le risposte di gape valvola di ostriche, Crassostrea virginica, ipossia diel-ciclismo e pH ciclica.

Video: A Strain Gauge Monitor SGM for Continuous Valve Gape Measurements in Bivalve Molluscs in Response to Laboratory Induced Diel-cycling Hypoxia and pH

A Simple Approach to Manipulate Dissolved Oxygen for Animal Behavior Observations

The ability to manipulate dissolved oxygen (DO) in a laboratory setting has significant application to investigate a number of ecological and organismal behavior questions. The protocol described here provides a simple, reproducible, and controlled method to manipulate DO to study behavioral response in aquatic organisms resulting from hypoxic and anoxic conditions. While performing degasification of water with nitrogen is commonly used in laboratory settings, no explicit method for ecological (aquatic) application exists in the literature, and this protocol is the first to describe a protocol to degasify water to observe organismal response. This technique and protocol were developed for direct application for aquatic macroinvertebrates; however, small fish, amphibians, and other aquatic vertebrates could be easily substituted. It allows for easy manipulation of DO levels ranging from 2 mg/L to 11 mg/L with stability for up to a 5 min animal-observation period. Beyond a 5 min observation period water temperatures began to rise, and at 10 min DO levels became too unstable to maintain. The protocol is scalable to the study organism, reproducible, and reliable, allowing for rapid implementation into introductory teaching labs and high-level research applications. The expected results of this technique should relate dissolved oxygen changes to behavioral responses of organisms.

This article describes a simple and reproducible protocol to manipulate dissolved oxygen conditions in a laboratory setting for animal behavior studies. This protocol may be used in both teaching and research laboratory settings to evaluate organismal response of macroinvertebrates, fishes, or amphibians to changes in dissolved oxygen concentration.

Un approccio semplice per manipolare ossigeno disciolto per Osservazioni Comportamento animale

The ability to manipulate dissolved oxygen (DO) in a laboratory setting has significant application to investigate a number of ecological and organismal ...

Ricerca

Ambiente

Monitoring the Wall Mechanics During Stent Deployment in a Vessel

Clinical trials have reported different restenosis rates for various stent designs1. It is speculated that stent-induced strain concentrations on the arterial wall lead to tissue injury, which initiates restenosis2-7. This hypothesis needs further investigations including better quantifications of non-uniform strain distribution on the artery following stent implantation. A non-contact surface strain measurement method for the stented artery is presented in this work. ARAMIS stereo optical surface strain measurement system uses two optical high speed cameras to capture the motion of each reference point, and resolve three dimensional strains over the deforming surface8,9. As a mesh stent is deployed into a latex vessel with a random contrasting pattern sprayed or drawn on its outer surface, the surface strain is recorded at every instant of the deformation. The calculated strain distributions can then be used to understand the local lesion response, validate the computational models, and formulate hypotheses for further in vivo study.

Stent-induced arterial strain distributions are characterized using an optical surface strain measurement system. This visualization technique is used to gain insights into the impact of stent implantation on the host vessel.

Monitoraggio dei Mechanics parete durante la distribuzione stent in un recipiente

Clinical trials have reported different restenosis rates for various stent designs1. It is speculated that stent-induced strain concentrations on the ...

Bioingegneria

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol for performing in situ juvenile exposure tests within oligotrophic river catchments over one-month and three-month periods. Two methods (in both modifications) are presented to evaluate the juvenile growth and survival rate. The methods and modifications differ in value for the locality bioindication and each has its benefits as well as limitations. The sandy cage method works with a large set of individuals, but only some of the individuals are measured and the results are evaluated in bulk. In the mesh cage method, the individuals are kept and measured separately, but a low individual number is evaluated. The open water exposure modification is relatively easy to apply; it shows the juvenile growth potential of sites and can also be effective for water toxicity testing. The within-bed exposure modification needs a high workload but is closer to the conditions of a natural juvenile environment and it is better for reporting the real suitability of localities. On the other hand, more replications are needed in this modification due to its high-hyporheic environment variability.

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

In situ bioindications enable determination of the suitability of an environment for endangered mussel species. We describe two methods based on the juvenile exposure of freshwater pearl mussels in cages to oligotrophic river habitats. Both methods are implemented in variants for open water and hyporheic water environments.

Bioindicazione test di idoneità ambiente Stream per giovani d'acqua dolce perla cozze utilizzando metodi di esposizione In Situ

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol ...

Quantitative and Temporal Control of Oxygen Microenvironment at the Single Islet Level

Simultaneous oxygenation and monitoring of glucose stimulus-secretion coupling factors in a single technique is critical for modeling pathophysiological states of islet hypoxia, especially in transplant environments. Standard hypoxic chamber techniques cannot modulate both stimulations at the same time nor provide real-time monitoring of glucose stimulus-secretion coupling factors. To address these difficulties, we applied a multilayered microfluidic technique to integrate both aqueous and gas phase modulations via a diffusion membrane. This creates a stimulation sandwich around the microscaled islets within the transparent polydimethylsiloxane (PDMS) device, enabling monitoring of the aforementioned coupling factors via fluorescence microscopy. Additionally, the gas input is controlled by a pair of microdispensers, providing quantitative, sub-minute modulations of oxygen between 0-21%. This intermittent hypoxia is applied to investigate a new phenomenon of islet preconditioning. Moreover, armed with multimodal microscopy, we were able to look at detailed calcium and KATP channel dynamics during these hypoxic events. We envision microfluidic hypoxia, especially this simultaneous dual phase technique, as a valuable tool in studying islets as well as many ex vivo tissues.

Microfluidic oxygen control confers more than just convenience and speed over hypoxic chambers for biological experiments. Especially when implemented via diffusion through a membrane, microfluidic oxygen can provide simultaneous liquid and gas phase modulations at the microscale-level. This technique enables dynamic multi-parametric experiments critical for studying islet pathophysiology.

Controllo quantitativo e temporale di ossigeno Microenvironment al Islet Single Level

Simultaneous oxygenation and monitoring of glucose stimulus-secretion coupling factors in a single technique is critical for modeling pathophysiological ...

Design and Use of an Apparatus for Quantifying Bivalve Suspension Feeding at Sea

As shellfish aquaculture moves from coastal embayments and estuaries to offshore locations, the need to quantify ecosystem interactions of farmed bivalves (i.e., mussels, oysters, and clams) presents new challenges. Quantitative data on the feeding behavior of suspension-feeding mollusks is necessary to determine important ecosystem interactions of offshore shellfish farms, including their carrying capacity, the competition with the zooplankton community, the availability of trophic resources at different depths, and the deposition to the benthos. The biodeposition method is used to quantify feeding variables in suspension-feeding bivalves in a natural setting and represents a more realistic proxy than laboratory experiments. This method, however, relies upon a stable platform to satisfy the requirements that water flow rates supplied to the shellfish remain constant and the bivalves are undisturbed. A flow-through device and process for using the biodeposition method to quantify the feeding of bivalve mollusks were modified from a land-based format for shipboard use by building a two-dimensional gimbal table around the device. Planimeter data reveal a minimal pitch and yaw of the chambers containing the test shellfish despite boat motion, the flow rates within the chambers remain constant, and operators are able to collect the biodeposits (feces and pseudofeces) with sufficient consistency to obtain accurate measurements of the bivalve clearance, filtration, selection, ingestion, rejection, and absorption at offshore shellfish aquaculture sites.

A flow-through device for using the biodeposition method to quantify filtration and feeding behavior of bivalve mollusks was modified for shipboard use. A two-dimensional gimbal table built around the device isolates the apparatus from boat motion, thereby allowing the accurate quantification of bivalve filtration variables at offshore shellfish aquaculture sites.

Progettazione e l'uso di un apparato per quantificare bivalvi sospensione alimentazione in mare

As shellfish aquaculture moves from coastal embayments and estuaries to offshore locations, the need to quantify ecosystem interactions of farmed bivalves ...

Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents.

Gastrointestinal dysfunction remains a major cause of morbidity and mortality. Indeed, gastrointestinal (GI) motility in health and disease remains an area of productive research with over 1,400 published animal studies in just the last 5 years. Numerous techniques have been developed for quantifying smooth muscle activity of the stomach, small intestine, and colon. In vitro and ex vivo techniques offer powerful tools for mechanistic studies of GI function, but outside the context of the integrated systems inherent to an intact organism. Typically, measuring in vivo smooth muscle contractions of the stomach has involved an anesthetized preparation coupled with the introduction of a surgically placed pressure sensor, a static pressure load such as a mildly inflated balloon or by distending the stomach with fluid under barostatically-controlled feedback. Yet many of these approaches present unique disadvantages regarding both the interpretation of results as well as applicability for in vivo use in conscious experimental animal models. The use of dual element strain gages that have been affixed to the serosal surface of the GI tract has offered numerous experimental advantages, which may continue to outweigh the disadvantages. Since these gages are not commercially available, this video presentation provides a detailed, step-by-step guide to the fabrication of the current design of these gages. The strain gage described in this protocol is a design for recording gastric motility in rats. This design has been modified for recording smooth muscle activity along the entire GI tract and requires only subtle variation in the overall fabrication. Representative data from the entire GI tract are included as well as discussion of analysis methods, data interpretation and presentation.

Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents.

The in vivo measurement of smooth muscle contractions along the gastrointestinal tract of laboratory animals remains a powerful, though underutilized, technique. Flexible, dual element strain gages are not commercially available and require fabrication. This protocol describes the construction of reliable, inexpensive strain gages for acute or chronic implantation in rodents.

Fabbricazione e impianto di miniatura a doppio elemento Estensimetri per misurazione<em&gt; In Vivo</em&gt; Gastrointestinale Contrazioni nei roditori.

Gastrointestinal dysfunction remains a major cause of morbidity and mortality. Indeed, gastrointestinal (GI) motility in health and disease remains an ...

Impedance Pneumography for Minimally Invasive Measurement of Heart Rate in Late Stage Invertebrates

Temperatures in oceans are increasing rapidly as a consequence of widespread changes in world climates. As organismal physiology is heavily influenced by environmental temperature, this has the potential to alter thermal physiological performance in a variety of marine organisms. Using the American lobster (Homarus americanus) as a model organism, this protocol describes the use of impedance pneumography to understand how cardiac performance in late stage invertebrates changes under acute thermal stress. The protocol presents a minimally invasive technique that allows for real-time collection of heart rate during a temperature ramping experiment. Data are easily manipulated to generate an Arrhenius plot that is used to calculate Arrhenius break temperature (ABT), the temperature at which heart rate begins to decline with increasing temperatures. This technique can be used in a variety of late stage invertebrates (i.e., crabs, mussels, or shrimps). Although the protocol focuses solely on the impact of temperature on cardiac performance, it can be modified to understand the potential for additional stressors (e.g., hypoxia or hypercapnia) to interact with temperature to influence physiological performance. Thus, the method has potential for wide-ranging applications to further understand how marine invertebrates respond to acute changes in the environment.

Measuring heart rate during a thermal challenge provides insight into physiological responses of organisms as a consequence of acute environmental change. Using the American lobster (Homarus americanus) as a model organism, this protocol describes the use of impedance pneumography as a relatively noninvasive and nonlethal approach to measure heart rate in late stage invertebrates.

Pneumografia impedibile per la misurazione minimamente invasiva della frequenza cardiaca negli invertebrati in fase avanzata

Temperatures in oceans are increasing rapidly as a consequence of widespread changes in world climates. As organismal physiology is heavily influenced by ...

The ex vivo Isolated Skeletal Microvessel Preparation for Investigation of Vascular Reactivity

The isolated microvessel preparation is an ex vivo preparation that allows for examination of the different contributions of factors that control vessel diameter, and thus, perfusion resistance1-5. This is a classic experimental preparation that was, in large measure, initially described by Uchida et al.15 several decades ago. This initial description provided the basis for the techniques that was extensively modified and enhanced, primarily in the laboratory of Dr. Brian Duling at the University of Virginia6-8, and we present a current approach in the following pages. This preparation will specifically refer to the gracilis arteriole in a rat as the microvessel of choice, but the basic preparation can readily be applied to vessels isolated from nearly any other tissue or organ across species9-13. Mechanical (i.e., dimensional) changes in the isolated microvessels can easily be evaluated in response to a broad array of physiological (e.g., hypoxia, intravascular pressure, or shear) or pharmacological challenges, and can provide insight into mechanistic elements comprising integrated responses in an intact, although ex vivo, tissue. The significance of this method is that it allows for facile manipulation of the influences on the integrated regulation of microvessel diameter, while also allowing for the control of many of the contributions from other sources, including intravascular pressure (myogenic), autonomic innervation, hemodynamic (e.g., shear stress), endothelial dependent or independent stimuli, hormonal, and parenchymal influences, to provide a partial list. Under appropriate experimental conditions and with appropriate goals, this can serve as an advantage over in vivo or in situ tissue/organ preparations, which do not readily allow for the facile control of broader systemic variables. 
The major limitation of this preparation is essentially the consequence of its strengths. By definition, the behavior of these vessels is being studied under conditions where many of the most significant contributors to the regulation of vascular resistance have been removed, including neural, humoral, metabolic, etc. As such, the investigator is cautioned to avoid over-interpretation and extrapolation of the data that are collected utilizing this preparation. The other significant area of concern with regard to this preparation is that it can be very easy to damage cellular components such as the endothelial lining or the vascular smooth muscle, such that variable source of error can be introduced. It is strongly recommended that the individual investigator utilize appropriate measurements to ensure the quality of the preparation, both at the initiation of the experiment and periodically throughout the course of a protocol.

The ex vivo Isolated Skeletal Microvessel Preparation for Investigation of Vascular Reactivity

An ex vivo preparation is described for isolation of the largest gracilis muscle resistance arterioles for interrogation of both vascular responses to vasoactive stimuli and the assessment of basic structural properties via passive wall mechanics.

Il Ex vivo Preparazione isolato microvasi scheletrico per le Indagini di reattività vascolare

The isolated  microvessel preparation is an ex vivo preparation that allows for examination of the different contributions of  factors that control vessel ...

Biologia

Mechano-Node-Pore Sensing: A Rapid, Label-Free Platform for Multi-Parameter Single-Cell Viscoelastic Measurements

Cellular mechanical properties are involved in a wide variety of biological processes and diseases, ranging from stem cell differentiation to cancer metastasis. Conventional methods for measuring these properties, such as atomic force microscopy (AFM) and micropipette aspiration (MA), capture rich information, reflecting a cell's full viscoelastic response; however, these methods are limited by very low throughput. High-throughput approaches, such as real-time deformability cytometry (RT-DC), can only measure limited mechanical information, as they are often restricted to single-parameter readouts that only reflect a cell's elastic properties. In contrast to these methods, mechano-node-pore sensing (mechano-NPS) is a flexible, label-free microfluidic platform that bridges the gap in achieving multi-parameter viscoelastic measurements of a cell with moderate throughput. A direct current (DC) measurement is used to monitor cells as they transit a microfluidic channel, tracking their size and velocity before, during, and after they are forced through a narrow constriction. This information (i.e., size and velocity) is used to quantify each cell's transverse deformation, resistance to deformation, and recovery from deformation. In general, this electronics-based microfluidic platform provides multiple viscoelastic cell properties, and thus a more complete picture of a cell's mechanical state. Because it requires minimal sample preparation, utilizes a straightforward electronic measurement (in contrast to a high-speed camera), and takes advantage of standard soft lithography fabrication, the implementation of this platform is simple, accessible, and adaptable to downstream analysis. This platform's flexibility, utility, and sensitivity have provided unique mechanical information on a diverse range of cells, with the potential for many more applications in basic science and clinical diagnostics.

Presented here is a method to mechanically phenotype single cells using an electronics-based microfluidic platform called mechano-node-pore sensing (mechano-NPS). This platform maintains moderate throughput of 1-10 cells/s while measuring both the elastic and viscous biophysical properties of cells.

Rilevamento meccano-nodo-pore: una piattaforma rapida e senza etichette per misure viscoelastiche monocellulari multiparametriche

Cellular mechanical properties are involved in a wide variety of biological processes and diseases, ranging from stem cell differentiation to cancer ...

Physiological Characterization of the Coral Holobiont Using a New Micro-Respirometry Tool

Metabolic activity, defined as the sum of organismal processes that involve energy, is of critical importance in understanding the function and evolution of life on earth. Measuring organismal metabolic rates is, therefore, at the center of explaining the physiological states of organisms, their ecological roles, and the impact of environmental change on species within terrestrial and aquatic ecosystems. On coral reefs, measures of metabolism have been used to quantify symbiosis functioning between corals and their obligate algal symbionts (Symbiodiniaceae), as well as assess how environmental stressors, including climate change, will impact coral health. Despite this significance, there is a lack of methods, and therefore data, relating to metabolic rate measurements in coral offspring, likely due to their small size. To address this gap, this study aimed to develop a custom setup for measuring the respiration of small (millimeter size range) marine animal ecologies. This low cost and easy setup should allow for the improved measurement of metabolic rate. This will be essential for applied ecological research utilizing the sexual production of corals for reef restoration.

This protocol describes the setup and running of a micro-respirometry system that can be employed to investigate the physiological features of the coral holobiont.

Caratterizzazione fisiologica dell'olobionte di corallo mediante un nuovo strumento di micro-respirometria

Metabolic activity, defined as the sum of organismal processes that involve energy, is of critical importance in understanding the function and evolution ...