Long-term potentiation is associated with increases in quantal content and quantal amplitude.

Long-term potentiation (LTP) of synaptic transmission in CA1 neurons of the hippocampus, elicited by the conjunction of presynaptic firing and postsynaptic depolarization, is an important model of plasticity, which may underlie memory storage. Although induction of LTP takes place in the postsynaptic cell, it is not clear whether it is expressed through an enhancement of transmitter release or through an increased postsynaptic response to the same amount of transmitter. Analysis of the trial-to-trial amplitude fluctuations of synaptic signals, that is quantal analysis, gives an important insight into the probabilistic mechanisms of transmission, although attempts to apply it to the mode of expression of LTP have so far yielded inconsistent results, at least in part because they have relied on models of transmitter release that have not been confirmed experimentally. Here we report clear evidence for quantal fluctuation in a subset of cells. Induction of LTP in these cells causes abrupt increases in either quantal content or quantal amplitude, or both. This shows that two different mechanisms can underlie the maintenance of LTP.     

Interaction of spinal and hypothalamic thermodetectors in body temperature regulation of the conscious dog

Zusammenfassung An wachen Hunden wurden kombinierte thermische Reizungen von Rückenmark und Hypothalamus bei verschiedenen Lufttemperaturen durchgeführt. Die Untersuchungen führten zu dem Ergebnis, dass die thermischen Afferenzen aus Rückenmark, Hypothalamus und Haut in einem gemeinsamen Zentrum zu einer koordinierten effektorischen Leistung des temperaturregulierenden Systems verarbeitet werden. Die Funktion der hypothalamischen und der spinalen thermosensiblen Strukturen erwies sich dabei als völlig gleichartig.     

Redundant regulation of localization and protein stability of DmPar3

Apical–basal polarity is an important characteristic of epithelia and Drosophila neural stem cells. The conserved Par complex, which consists of the atypical protein kinase C and the scaffold proteins Baz and Par6, is a key player in the establishment of apical–basal cell polarity. Membrane recruitment of Baz has been reported to be accomplished by several mechanisms, which might function in redundancy, to ensure the correct localization of the complex. However, none of the described interactions was sufficient to displace the protein from the apical junctions. Here, we dissected the role of the oligomerization domain and the lipid-binding motif of Baz in vivo in the Drosophila embryo. We found that these domains function in redundancy to ensure the apical junctional localization of Baz: inactivation of only one domain is not sufficient to disrupt the function of Baz during apical–basal polarization of epithelial cells and neural stem cells. In contrast, mutation of both domains results in a strongly impaired protein stability and a phenotype characterized by embryonic lethality and an impaired apical–basal polarity in the embryonic epithelium and neural stem cells, resembling a baz-loss of function allele. Strikingly, the binding of Baz to the transmembrane proteins E-Cadherin, Echinoid, and Starry Night was not affected in this mutant protein. Our findings reveal a redundant function of the oligomerization and the lipid-binding domain, which is required for protein stability, correct subcellular localization, and apical–basal cell polarization.     

The role of mammalian ionotropic receptors in synaptic plasticity: LTP, LTD and epilepsy

Synaptic plasticity is the foremost candidate mechanism to explain the rapid acquisition of memories. In the mammalian brain, the NMDA subclass of glutamate receptors plays a central role in the induction of several forms of use-dependent plasticity. The finding that modifications in synaptic strength are largely expressed by receptors of the AMPA subclass has focused attention on molecular mechanisms that affect their function and targeting. Receptor plasticity has also been reported in pathological situations, notably in animal and human forms of epilepsy. Which of these changes are causally implicated in the generation of seizures, and which may be compensatory or neuroprotective adaptations, has not been fully resolved.     

Modified Dye for Water-Fast Ink-Jet Printing

A quaternary ammonium compound containing amino acid residue was synthesized by Converting 3-chloro-2-hydroxy-propyalkyldimethylammonium chlorides into its epoxide derivatives, then attaching an amino acid to the epoxide derivatives synthesized a quaternary ammonium compound containing amino acid residue. Modified dyes were prepared by the ionotropy of anionic dyes with the quaternary ammonium compound containing amino acid residue. It was discovered that the modified dyes exhibited an excellent pH controllable solubility. These modified dyes have good water solubility at pH> 8.0, but they were water insoluble at pH < 6.5. On the printing paper, modified dyes in water-based ink-jet print ink could convert to water insoluble form and give prints excellent water fastness.