Comparison of instrumental neutron activation analysis of geological materials with other multielement techniques

Results obtained for 12 elements in approximately 1600 rocks by instrumental neutron activation analysis (INAA) are compared with those obtained by ICP emission spectrometry (ICP-ES), XRF, and atomic-absorption spectrometry (AAS). Sample duplicates and two controls are used to evaluate the precison of the methods investigated. Application of a method (Maximum Likelihood Functional Relationship) to determine and quantify rotational and translational bias is demonstrated. The elements Na, Fe, Ba, Co, Cr, La, Ni and Rb can be determined in rocks by INAA with sufficient sensitivity and precision, whereas the determination of Ag, Yb, Zn and Zr suffers from inadequate sensitivity. Good agreement is seen in the results for Na (by INAA, ICP-ES and XRF) and AG (INAA and AAS). A significant positive bias (13% or less) is evident in the comparison of results by INAA and ICP-ES or XRF for Cr, Ba, Ni and Fe over a wide range of concentration. A similar trend, though less significant, is observed for the elements Yb, Rb, La and Co; the upper limit of concentration for satisfactory determination is within a decade of the highest detection limit for these elements. Rotational and translational bias is evident for Zn in the comparison of data obtained by INAA and ICP-ES, the results by INAA being appreciably lower above about 400 ppm Zn.     

Expression of ionotropic glutamate receptors in the retina of the rdta transgenic mouse

Background

One mechanism that directs the action of the second messengers, cAMP and diacylglycerol, is the compartmentalization of protein kinase A (PKA) and protein kinase C (PKC). A-kinase anchoring proteins (AKAPs) can recruit both enzymes to specific subcellular locations via interactions with the various isoforms of each family of kinases. We found previously that a new class of AKAPs, dual-specific AKAPs, denoted D-AKAP1 and D-AKAP2, bind to RIα in addition to the RII subunits.

Results

Immunohistochemistry and confocal microscopy were used here to determine that D-AKAP1 colocalizes with RIα at the postsynaptic membrane of the vertebrate neuromuscular junction (NMJ) and the adjacent muscle, but not in the presynaptic region. The labeling pattern for RIα and D-AKAP1 overlapped with mitochondrial staining in the muscle fibers, consistent with our previous work showing D-AKAP1 association with mitochondria in cultured cells. The immunoreactivity of D-AKAP2 was distinct from that of D-AKAP1. We also report here that even though the PKA type II subunits (RIIα and RIIβ) are localized at the NMJ, their patterns are distinctive and differ from the other R and D-AKAP patterns examined. PKCβ appeared to colocalize with the AKAP, gravin, at the postsynaptic membrane.

Conclusions

The kinases and AKAPs investigated have distinct patterns of colocalization, which suggest a complex arrangement of signaling micro-environments. Because the labeling patterns for RIα and D-AKAP 1 are similar in the muscle fibers and at the postsynaptic membrane, it may be that this AKAP anchors RIα in these regions. Likewise, gravin may be an anchor of PKCβ at the NMJ.