N-Methyl-D-Aspartate receptors in acquisition of the short-term memory in the honeybeeApis mellifera

Role of NMDA receptors in the process of associative learning has been studied in the honeybeeApis mellifera L. in behavior experiments, using method of conditional reflexes. To determine pharmacological profile of NMDA receptors, effects of Mg²⁺ ions, NMDA, glycine (Gly), antagonist of the glycine site 5,7-dichlorokynurenic acid (DCK), competitive antagonists of NMDA receptors: D,L-2-aminophosphovalerate (APV), L-2-aminophosphobutyrate (APB), and D-glutamyl-aminomethylphosphonic acid (GAMP) as well of antagonists of NMDA receptor ion channels MK-801 and ketamine (Ket) were studied on acquisition of alimentary conditional reflex and its retention in memory. NMDA increased capacity for learning by stimulating shortterm memory. The NMDA receptor co-agonist Gly activated this NMDA effect. DCK eliminated the NMDA and Gly stimulatoty effects. All tested antagonists at millimolar concentrations inhibited associative function. The data obtained confirm our hypothesis about participation of NMDA receptors in processes of formation of short-term memory in the honeybeeApis mellifera and suggest that functional characteristics of the NMDA receptors involved in the process of associative learning in the honeybee resemble those in mammals.     

Synthesis of a 3-methyluridine phosphoramidite to investigate the role of methylation in a ribosomal RNA hairpin.

The synthesis of a 5'-O-BzH-2'-O-ACE-protected-3-methyluridine phosphoramidite is reported [BzH, benzhydryloxy-bis(trimethylsilyloxy)silyl; ACE, bis(2-acetoxyethoxy)methyl]. The phosphoramidite was employed in solid-phase RNA synthesis to generate a series of RNA hairpins containing single or multiple modifications, including the common nucleoside pseudouridine. Three 19-nucleotide hairpin RNAs that represent the 1920-loop region (G(1906)-C(1924)) of Escherichia coli 23S ribosomal RNA were generated. Modifications were present at positions 1911, 1915, and 1917. The stabilities and structures of the three RNAs were examined by using thermal melting, circular dichroism, and NMR spectroscopy     

Scanning electron microscope study of Pseudomonas putida colonies.

Pseudomonas putida colonies were examined by scanning electron microscope. A variety of cell morphologies, multicellular arrangements, and extracellular materials were observed in the fixed material. Different regions of a single colony showed characteristic organizations of these architectural elements. In some cases, the detailed microstructure of the fixed colony surfaces observed by scanning electron microscopy could be correlated with macroscopic patterns visualized by histochemical staining and surface relief photography of live colonies. Extracellular materials were seen to extend onto the agar surface beyond the boundaries of the cell mass, and the final structures of these materials, after fixation and desiccation, were colony specific. The significance of these features of colony microstructure for formulating hypotheses about the control of colony morphogenesis is discussed.     

Ultrastructural characteristics of the neocortex during rehabilitation from the sequelae of long-term protein-energy deficiency

Electron microscopy of mouse neocortex was carried out during rehabilitation following long-term protein-caloric deficiency. Food rehabilitation led to partial recovery of brain ultrastructure, however, a high neuronal level of secondary lysosoms and lipofuscin bodies was preserved, with the changes in the spine apparatus and synaptic contacts persisting in neuropile. Carnitine addition to food during rehabilitation increased the number of free ribosomes in cortical neurons. A substantial development of granular endoplasmic reticulum was observed. A greater number of spine apparatus cisterns was detected, however, like in conventional rehabilitation, the width of synaptic clefts and postsynaptic densities remained narrower than in control mice.     

Disruption of energy metabolism and smoltification during exposure of juvenile atlantic salmon (Salmo salar) to low pH

Juvenile Atlantic salmon were held for 76 days at pH 4.7 during the period when the final stages of smoltification normally occur. Control salmon (pH 6.5) had significant increases in weight, length and liver somatic index which were not observed in those held at low pH. Condition factor decreased in both groups but to a significantly greater extent in the low pH group. After 15 days levels of ADP and glucose were higher and AEC, CP and glycogen were lower in muscles of salmon exposed to low pH. These qualitative differences were maintained until the end of the experiment. ATP and total adenylate concentrations in muscle were lower after 62 days of exposure to low pH compared to controls. The levels of ATP, total adenylates, AEC and glucose were consistently higher in livers of salmon exposed to low pH than those of controls. There were no differences in liver concentrations of AMP, CP and glycogen between the two treatments or with time of exposure within each treatment. The results suggest that exposure of juvenile Atlantic salmon to low pH increased gluconeogenesis and decreased food intake to the detriment of growth.     

Effects of water flow on transmembrane ionic currents in neurons of Helix pomatia and in squid giant axons

1. The effects of water flow through the membrane produced by an osmotic gradient on the ionic currents in Helix neurons and in squid giant axons were studied. 2. Outward water flow had a marked effect on the ionic currents. 3. Cell volume diminution in hypertonic solution was accompanied by a decrease in the number of functioning ionic channels in the neurons. 4. Decrease of the tonicity of the external 10(-8) M TTX-containing solution leads to a transient recovery of the action potentials of the squid.     

Separation of Legionella pneumophila proteases and purification of a protease which produces lesions like those of Legionnaires' disease in guinea pig lung

Six discrete protease activities were recovered from the supernatant broth of Legionella pneumophila cultures by ion-exchange chromatography. One of these demonstrated in vitro activity against collagen, casein and gelatin. When administered into the lungs of guinea-pigs this protease elicited lesions which were pathologically similar to those seen in clinical and experimentally induced Legionnaires' disease.