A self-referencing glutamate biosensor for measuring real time neuronal glutamate flux

McLamore, Eric S.; Mohanty, Subhashree; Shi, Jin; Claussen, Jonathan C.; Jedlicka, Sabrina S.; Rickus, Jenna L.; Porterfield, D. Marshall

doi:10.1016/j.jneumeth.2010.03.001

Cited by 64 publications

(75 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The problem is amplified when trying to measure rapidly oscillating basal signals. There are methods for monitoring external oscillations of ions and metabolites using vibrating probes (Jaffe and Nuccitelli, 1974; Shabala et al, 1997) and recently developed, self-referencing biosensors (Porterfield, 2007;McLamore et al, 2010), respectively. Similar technical advances are needed for studying fluxes within cells.…”

mentioning

confidence: 99%

Basal Signaling Regulates Plant Growth and Development

Boss

Sederoff

et al. 2010

Plant Physiology

View full text Add to dashboard Cite

The term signal transduction refers to the classical paradigm where an external stimulus is sensed and initiates an increase in second messengers. Each second messenger transmits and amplifies the signal by activating a subset of downstream pathways. This complex network of interwoven downstream events ultimately converges to produce measurable responses. While the paradigms for signal transduction are well known, little consideration has been given to the second messengers in the nonstimulated cell, the basal signal, and yet, basal signals also impact plant growth and development.Basal signals are low levels of oscillating second messengers that are being sensed by the cell. These are difficult to measure and are often considered to be background noise. Not surprisingly, there is a dearth of knowledge about how plants respond to this constant flux of signaling metabolites or about how basal signals define homeostasis or contribute to species diversity. Both genetics and environment will define the basal signal of a cell. To truly understand how plants regulate growth and development, future research must focus on understanding how basal signals regulate fundamental metabolism.Our hypothesis is that in a nonstimulated cell, a low level of basal signal will constitutively repress some downstream events and stimulate others. If this is true, then lowering the basal level of a second messenger should derepress or enhance those downstream events specifically targeted by this second messenger, while events that depend on the basal level of second messenger will not be activated (Fig. 1).Monitoring rapid, transient changes in second messengers within stimulated cells is challenge enough. The problem is amplified when trying to measure rapidly oscillating basal signals. There are methods for monitoring external oscillations of ions and metabolites using vibrating probes (Jaffe and Nuccitelli, 1974; Shabala et al., 1997) and recently developed, self-referencing biosensors (Porterfield, 2007;McLamore et al., 2010), respectively. Similar technical advances are needed for studying fluxes within cells. In vivo fluorescent reporters can indicate changes in stimulus-induced oscillations within single cells (Monshausen et al., 2008(Monshausen et al., , 2009); however, the fluorophores, by necessity, are selected to report signals above the background noise so that the basal signals of a nonstimulated cell are often below the limits of detection. Furthermore, the basal levels of second messengers are usually at or below the limits of detection for metabolomic analyses, and metabolic fluxes are difficult to assess with metabolomics (Fernie et al., 2005).Alternative approaches are needed to assess the impact of basal signals. In principle, if one lowered a basal signal, downstream events regulated by the second messenger in the nonstimulated cell would be revealed. Because basal signals are inherently a part of normal metabolism, it is difficult to lower basal signals; however, there are several examples where expression of gen...

show abstract

mentioning

confidence: 99%

Basal Signaling Regulates Plant Growth and Development

Boss

Sederoff

et al. 2010

Plant Physiology

View full text Add to dashboard Cite

show abstract

“…This result could be due to reduced diffusivity of oxygen through the layer; however, the alternative conclusion is that the magnitude of the flux is simply decreased by the experimental artifact of an increased distance between the optrode and the islet. Flux is calculated from the concentration gradient, which theoretically and experimentally decreases with distance from the source or sink (30,32), in this case the islet surface. The coating imposes at least one to a few micrometers distance between the islet and the surface of the coating and therefore the islet surface and the optrode.…”

Section: Discussionmentioning

confidence: 99%

Mouse and human islets survive and function after coating by biosilicification

Jaroch

Madangopal

et al. 2013

American Journal of Physiology-Endocrinology and Metabolism

View full text Add to dashboard Cite

Inorganic materials have properties that can be advantageous in bioencapsulation for cell transplantation. Our aim was to engineer a hybrid inorganic/soft tissue construct by inducing pancreatic islets to grow an inorganic shell. We created pancreatic islets surrounded by porous silica, which has potential application in the immunoprotection of islets in transplantation therapies for type 1 diabetes. The new method takes advantage of the islet capsule surface as a template for silica formation. Mouse and human islets were exposed to medium containing saturating silicic acid levels for 9 -15 min. The resulting tissue constructs were then cultured for up to 4 wk under normal conditions. Scanning electron microscopy and energy dispersive Xray spectroscopy was used to monitor the morphology and elemental composition of the material at the islet surface. A cytokine assay was used to assess biocompatibility with macrophages. Islet survival and function were assessed by confocal microscopy, glucose-stimulated insulin release assays, oxygen flux at the islet surface, expression of key genes by RT-PCR, and syngeneic transplant into diabetic mice. islet; encapsulation; silica; coating; tissue engineering TO CREATE 3D TISSUE CONSTRUCTS for transplantation therapies, cells are typically encapsulated within organic polymers, either synthetic or natural, such as collagen or alginate. For applications requiring protection from the immune system, however, inorganic or hybrid (inorganic/organic) materials may offer a different set of useful functions and properties to be used as alternatives to or in conjunction with the organic polymers. Porous silica is an attractive material for these applications because of its mesoporosity, potential to create hierarchical structures, optical transparency, capacity for biofunctionalization, performance in precision size exclusion, and bioactivity.Our work focuses on primary pancreatic islets because of their importance in therapies for type 1 diabetes. The Edmonton protocol of islet transplantation in humans (40) has demonstrated remarkable short-term success, with 80% of individuals achieving insulin independence at 1 yr posttransplant; however, this rate decreases to only about 10 -15% at 5 yr (3). Multiple mechanisms contribute to the progressive loss of graft function but likely include an immediate blood-mediated response (IBMR) (1, 37), poor revascularization and hypoxia (9, 16), and ongoing auto-and alloimmune responses (38). Protection of islets or stem cell-derived pseudo-islets by protective membranes could significantly improve transplant outcomes for patients.The sol-gel synthesis method of forming solid porous silica under biologically friendly temperatures and pH has been used to encapsulate first biomolecules and later living cells since the early 1990s. Early attempts to use silica as a microencapsulation matrix for islets employed bulk sol-gel techniques, resulting in islets encased in thick silica slabs or spheres (34, 35). These implants were able to supply enough insulin...

show abstract

“…Enzymes are usually immobilized on the electrode by polymer encapsulation or covalent linking (McLamore et al, 2010b;McLamore et al, 2011;Rickus et al, 2002;Shi et al, 2010). During biosensor operation, when analyte solution diffuses into the enzyme layer, a series of biochemical and electrochemical reactions will take place.…”

Section: Enzyme Based Biosensingmentioning

confidence: 99%

“…Electrochemical biosensors provide qualitative and quantitative information (Wang 1999) on the existence and concentration of the target compounds in the analyte in the form of current (amperometric biosensor) or voltage (potentiometric biosensor). A typical amperometric biosensor consists of three components: the analyte, the transduction element (electrode and conductive nanomaterials) and the biorecognition element (enzyme) (McLamore et al, 2010a;McLamore et al, 2010b;Shi et al, 2010). During biosensor operation, target compound in the sample is specifically recognized by the enzymes immobilized on the electrode.…”

Section: Introductionmentioning

confidence: 99%

“…To overcome these limitations, some groups used polymers with neutral pH such as silicate sol-gel for enzyme immobilization to preserve enzyme activity (Salimi et al, 2004) while some groups used electric methods such as cyclic voltammetry to control layer deposition (Llaudet et al, 2005;Smutok et al, 2006). Furthermore, to obtain better performance, nanomaterials including carbon nanotubes (CNTs) and metal nanomaterials are often involved in surface modification (McLamore et al, 2010a;McLamore et al, 2010b;Shi et al, 2010). Since different modification approaches result in quite distinct biosensor performance, problems with evaluating and comparing different approaches, and sorting out the optimal ones have arisen.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation