There are many diagnostic techniques and methods available for diagnosis of medically important microorganisms like bacteria, viruses, fungi and parasites. But, almost all these techniques and methods have some limitations or inconvenience. Most of these techniques are laborious, time consuming and with chances of false positive or false negative results. It warrants the need of a diagnostic technique which can overcome these limitations and problems. At present, there is emerging trend to use Fluorescence spectroscopy as a diagnostic as well as research tool in many fields of medical sciences. Here, we will critically discuss research studies which propose that Fluorescence spectroscopy may be an excellent diagnostic as well as excellent research tool in medical microbiology field with high sensitivity and specificity.
G protein-coupled receptors have been proposed to exist in signalosomes subject to agonist-driven shifts in the assembly disassembly equilibrium, affected by stabilizing membrane lipids and/or cortical actin restricting mobility. We investigated the highly homologous corticotropin-releasing factor receptors (CRFRs), CRFR1 and -2, which are different within their hydrophobic core. Agonist stimulation of CRFR1 and CRFR2 gave rise to similar concentration-response curves for cAMP accumulation, but CRFR2 underwent restricted collision coupling. Both CRFR1 and CRFR2 formed constitutive oligomers at the cell surface and recruited -arrestin upon agonist activation (as assessed by fluorescence resonance energy transfer microscopy in living cells). However, CRFR2, but not CRFR1, failed to undergo agonist-induced internalization. Likewise, agonist binding accelerated the diffusion rate of CRFR2 only (detected by fluorescence recovery after photobleaching and fluorescence correlation spectroscopy) but reduced the mobile fraction, which is indicative of local confinement. Fluorescence intensity distribution analysis demonstrated that the size of CRFR complexes was not changed. Disruption of the actin cytoskeleton abolished the agonist-dependent increase in CRFR2 mobility, shifted the agonist concentration curve for CRFR2 to the left, and promoted agonist-induced internalization of CRFR2. Our observations are incompatible with an agonist-induced change in monomer-oligomer equilibrium, but they suggest an agonist-induced redistribution of CRFR2 into a membrane microdomain that affords rapid diffusion but restricted mobility and that is stabilized by the actin cytoskeleton. Our data show that membrane anisotropy can determine the shape and duration of receptor-generated signals in a subtypespecific manner.Signal transduction via heterotrimeric G proteins is accomplished by a cycle of activation and deactivation of the G␣-subunit, which is achieved by receptor-catalyzed exchange of prebound GDP for GTP and GTP hydrolysis by the intrinsic GTPase of G␣, respectively. Superimposed on this GTPase cycle, there is a cycle of subunit dissociation and reassociation, in which the inactive heterotrimer G␣.GDP.␥ affords receptor docking, GTP binding drives subunit dissociation into G␣.GTP.Mg 2ϩ and G␥, and the GTPase-mediated hydrolysis promotes mutual inactivation of two G␣.GDP and G␥ by reassociation of the inactive heterotrimer G␣.GDP.␥. This model was established some 20 years ago, mainly by the study of reconstituted purified components (Freissmuth et al., 1989). However, since then, methods have become available that allow the tracking of the activity of individual components at the single-cell level. In several instances, these have led to observations that are incompat-
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