Neurotransmitter Specific,Cellular-Resolution Functional Brain Mapping Using Receptor Coated Nanoparticles: Assessment of the Possibility

Receptor coated resonant nanoparticles and quantum dots are proposed to provide a cellular-level resolution image of neural activities inside the brain. The functionalized nanoparticles and quantum dots in this approach will selectively bind to different neurotransmitters in the extra-synaptic regions of neurons. This allows us to detect neural activities in real time by monitoring the nanoparticles and quantum dots optically. Gold nanoparticles (GNPs) with two different geometries (sphere and rod) and quantum dots (QDs) with different sizes were studied along with three different neurotransmitters: dopamine, gamma-Aminobutyric acid (GABA), and glycine. The absorption/emission spectra of GNPs and QDs before and after binding of neurotransmitters and their corresponding receptors are reported. The results using QDs and nanorods with diameter 25nm and aspect rations larger than three were promising for the development of the proposed functional brain mapping approach.     

Antigens Associated with N- and L-Type Calcium Channels in Lambert-Eaton Myasthenic Syndrome

Abstract: In Lambert-Eaton myasthenic syndrome neurotransmitter release is reduced by an autoimmune response directed against the calcium channel complex of the nerve terminal. Autoantibodies were detected by immunoprecipitation assays using solubilized receptors labeled with ligands selective for N-type (¹²⁵I-ω conotoxin GVIA) and L-type ([³H]PN200-110) calcium channels. Sera with a high antibody titer (>3 n M ) against rat brain N-type channels contained autoantibodies that immunoprecipitated neuronal and muscle L-type channels. These IgG fractions stained a 55-kDa protein in immunoblots of purified skeletal muscle dihydropyridine receptor, suggesting that they contain autoantibodies against the β subunit of the calcium channel. A distinct antibody population in the same fractions reacted with a nerve terminal 65-kDa protein that is unrelated to the β subunit and displays properties similar to those of synaptotagmin.     

Field assessment of numerical impacts of coastal sewage disposal on fish larvae relative to natural variability

Sewage disposal in aquatic environments can have significant impacts on assemblages of organisms. There have been few field investigations on effects of sewage disposal on fish larvae. Data on abundances of larvae, current velocities and the size and shape of sewage plumes from point-source shoreline outfalls off Sydney (Australia) indicated that alongshore currents could transport large numbers of fish larvae into plumes, potentially affecting their health. Assemblages of fish larvae in surface sewage plumes differed to those in distant shelf (control) waters, but no such impacts were detected for assemblages in subsurface (20 m depth) waters beneath plumes. No predictable negative or positive numerical responses of fish larvae to sewage disposal were detected. Abundances of fish larvae fluctuated greatly in space and throughout time, and responses appeared to vary between taxa, outfalls and sampling periods. However, the large inherent level of natural spatial and temporal variability in abundances of larvae confounded the detection of possible impacts. Future field investigations need to focus on effects of sewage disposal on the health and condition of fish larvae. Designs for future field-based studies are discussed.     

Malaria Parasite-Infected Erythrocytes Secrete PfCK1, the Plasmodium Homologue of the Pleiotropic Protein Kinase Casein Kinase 1

Casein kinase 1 (CK1) is a pleiotropic protein kinase implicated in several fundamental processes of eukaryotic cell biology. Plasmodium falciparum encodes a single CK1 isoform, PfCK1, that is expressed at all stages of the parasite’s life cycle. We have previously shown that the pfck1 gene cannot be disrupted, but that the locus can be modified if no loss-of-function is incurred, suggesting an important role for this kinase in intra-erythrocytic asexual proliferation. Here, we report on the use of parasite lines expressing GFP- or His-tagged PfCK1 from the endogenous locus to investigate (i) the dynamics of PfCK1 localisation during the asexual cycle in red blood cells, and (ii) potential interactors of PfCK1, so as to gain insight into the involvement of the enzyme in specific cellular processes. Immunofluorescence analysis reveals a dynamic localisation of PfCK1, with evidence for a pool of the enzyme being directed to the membrane of the host erythrocyte in the early stages of infection, followed by a predominantly intra-parasite localisation in trophozoites and schizonts and association with micronemes in merozoites. Furthermore, we present strong evidence that a pool of enzymatically active PfCK1 is secreted into the culture supernatant, demonstrating that PfCK1 is an ectokinase. Our interactome experiments and ensuing kinase assays using recombinant PfCK1 to phosphorylate putative interactors in vitro suggest an involvement of PfCK1 in many cellular processes such as mRNA splicing, protein trafficking, ribosomal, and host cell invasion.     

Specific overproduction of very late antigen 1 integrin in two human neuroblastoma cell lines selected for resistance to detachment by an Arg-Gly-Asp-containing synthetic peptide

Very late antigen (VLA) 1 is a member of the family of integral plasma-membrane glycoproteins known as integrins. It is a heterodimer composed of an alpha subunit of Mr 200,000, noncovalently associated with a beta subunit of Mr 110,000 which is shared by other VLA molecules (VLA-2-5). Unlike most of the other VLA proteins which have been shown to be receptors for various extracellular matrix proteins, the ligand for VLA-1 is unknown. Utilizing polyclonal antisera against the human fibronectin receptor as well as alpha subunit-specific monoclonal antibodies and cDNA probes, we have been able to demonstrate that in two human neuroblastoma cell lines, IMR-32 and SK-N-SH, the common beta subunit is associated with alpha 1, alpha 2, alpha 3, and alpha 5 subunits. By culturing these two cell lines in the presence of a synthetic peptide, Gly-Arg-Gly-Asp-Ser-Pro, which contains the Arg-Gly-Asp cell attachment promotion tripeptide, we have isolated variant cell lines resistant to the detachment effects of this peptide. Peptide-resistant SK-N-SH and IMR-32 neuroblastoma cells exhibit weaker attachment to type I collagen and laminin, but a similar level of attachment to fibronectin as compared to the parental cells. Although the peptide-resistant variant cell lines proliferate at a rate similar to that of the parental cell lines, they stably overproduce (up to 20-fold) the alpha 1 subunit (VLA-1) specifically; and in the IMR-32 variant cells, the common beta 1 subunit is also overproduced. The level of expression of alpha 2 and alpha 3 subunits, however, is considerably reduced and that of the alpha 5 subunit is unchanged relative to the parental cells. These data suggest that the expression of integrin alpha subunits can be regulated differentially and independently of the beta subunit and that the VLA-1 heterodimer has an important function in mediating Arg-Gly-Asp-dependent cell adhesion or other phenotypic properties in human neuroblastoma cells.