Ribozyme-mediated RNA synthesis and replication in a model Hadean microenvironment.

Enzyme-catalyzed replication of nucleic acid sequences is a prerequisite for the survival and evolution of biological entities. Before the advent of protein synthesis, genetic information was most likely stored in and replicated by RNA. However, experimental systems for sustained RNA-dependent RNA-replication are difficult to realise, in part due to the high thermodynamic stability of duplex products and the low chemical stability of catalytic RNAs.

CB1 receptor antagonism impairs the induction of epileptiform activity by group I metabotropic glutamate receptor activation.

Exposure to the group I metabotropic glutamate receptor (mGluR) agonist dihydroxy phenylglycine (DHPG) induces epileptiform activity in the CA3 region of the hippocampus that persists following washout of DHPG. DHPG also can cause long-term depression of synaptic transmission, and at some synapses this may be mediated by endocannabinoids. We evaluated whether the selective cannabinoid type 1 (CB1) receptor antagonists SR 141716 or AM 251 could modify induction of epileptiform activity produced by DHPG exposure.

Ictal activity induced by group I metabotropic glutamate receptor activation and loss of afterhyperpolarizations.

Exposure to the group I metabotropic glutamate receptor (mGluR) agonist dihydroxyphenylglycine (DHPG) produces long-lasting changes in network excitability and epileptiform activity in the CA3 region of rat hippocampal slices that continues in the absence of the agonist and includes both interictal and more prolonged ictal-like activity. We evaluated the afterhyperpolarization (AHP) that follows repetitive neuronal firing in neurons exposed to DHPG and related the change in the AHP to the pattern of epileptiform activity. In contrast to neurons from control slices that had a robust AHP following neuronal depolarization and action potential generation, neurons that had been exposed to DHPG displayed a minimal AHP following depolarization.

Discovery of the butenyl-spinosyn insecticides: novel macrolides from the new bacterial strain Saccharopolyspora pogona.

A new bacterium, Saccharopolyspora pogona (NRRL30141) was discovered which produced a series of very potent insecticidal compounds structurally related to the 'classical' (i.e., C-21-ethyl) spinosyns.

Activity-dependent induction and maintenance of epileptiform activity produced by group I metabotropic glutamate receptors in the rat hippocampal slice.

Activation of group I metabotropic glutamate receptors (mGluRs) produces a long-lasting change in hippocampal excitability that persists in the absence of an agonist. Exposure to the group I mGluR agonist dihydroxyphenylglycine (DHPG) results in the induction of spontaneously occurring epileptiform activity in the CA3 region of rat hippocampal slices that includes both brief interictal discharges and longer synchronous activity that resembles seizure or ictal activity (>2s duration oscillating at a frequency greater than 2 Hz). We evaluated activity-dependent mechanisms for the induction and maintenance of epileptiform activity.