Alternative Pathways of Glucose Utilization in Brain; Changes in the Pattern of Glucose Utilization in Brain Resulting from Treatment of Rats with 6-Aminonicotinamide

The effect of 6-aminonicotinamide (6AN) treatment on the activities of alternative pathways of glucose metabolism in 20-day-old rat brain was evaluated by measurements of yields of 14CO2 from glucose labeled with 14C on carbons 1, 2, 3 + 4, or 6 and uniformly labeled glucose, and from the incorporation of 14C from specifically labeled glucose into lipids by brain slices from cerebral hemispheres and cerebellum. At the highest dose of 6AN used (35 mg/kg body weight) there was a significant decrease in the 14CO2 yields via the pentose phosphate pathway, the glycolytic route, tricarboxylic acid (TCA) cycle, and via the glutamate-gamma-aminobutyric acid pathway. Giving a graded series of doses (20-35 mg 6AN/kg body weight) revealed a hierarchy of responses in which the pentose phosphate pathway, lactate, glyceride-glycerol, and fatty acid formation were most sensitive, followed, in sequence, by the pyruvate dehydrogenase reaction, the glutamate-gamma-aminobutyrate route and, finally, the TCA cycle. The nature of the blocks in the various pathways was examined by the use of metabolite profiles.     

Protection against glucose-induced neuronal death by NAAG and GCP II inhibition is regulated by mGluR3

Glutamate carboxypeptidase II (GCP II) inhibition has previously been shown to be protective against long-term neuropathy in diabetic animals. In the current study, we have determined that the GCP II inhibitor 2-(phosphonomethyl) pentanedioic acid (2-PMPA) is protective against glucose-induced programmed cell death (PCD) and neurite degeneration in dorsal root ganglion (DRG) neurons in a cell culture model of diabetic neuropathy. In this model, inhibition of caspase activation is mediated through the group II metabotropic glutamate receptor, mGluR3. 2-PMPA neuroprotection is completely reversed by the mGluR3 antagonist (S)-alpha-ethylglutamic acid (EGLU). In contrast, group I and III mGluR inhibitors have no effect on 2-PMPA neuroprotection. Furthermore, we show that two mGluR3 agonists, the direct agonist (2R,4R)-4-aminopyrrolidine-2, 4-dicarboxylate (APDC) and N-acetyl-aspartyl-glutamate (NAAG) provide protection to neurons exposed to high glucose conditions, consistent with the concept that 2-PMPA neuroprotection is mediated by increased NAAG activity. Inhibition of GCP II or mGluR3 may represent a novel mechanism to treat neuronal degeneration under high-glucose conditions.     

Repeated use of Bacillus subtilis cell walls for copper binding

Purified cell walls from Bacillus subtilis were repeatedly suspended in 5 mm CuCl₂ and, after removing unbound Cu, were suspended in 1% (v/v) HNO₃ to release bound Cu. The walls were then regenerated by washing in H₂O. After five cycles, copper binding actually increased slightly, probably due to enhanced exposure of binding sites in the walls. Thus bacterial walls may be used repeatedly for metal removal during bioremediation of heavy metal pollution.R.J.C. McLean is with the Department of Biology, Southwest Texas State University, 601 University Drive, San Marcos, TX 78666-4616, USA A.M. Campbell is with the Department of Chemical Engineering, Queen's University, Kingston, Ontario, K7L 3N6, Canada. P.T. Khu is with the Department of Mining Engineering, Queen's University, Kingston, Ontario, K7L 3N6, Canada. A.T. Persaud, L.E. Bickerton and D. Beauchemin are with the Department of Chemistry, Queen's University, Kingston, Ontario, K7L 3N6, Canada.     

Male golden hamsters (<Emphasis Type="Italic">Mesocricetus auratus</Emphasis>) are more reactive than females to a visual predator cue

In most species of small mammals, males are exposed to higher levels of risk than females because they compete for mates, travel greater distances to find and procure mates, and/or defend a territory. This suggests that males and females might have different responses to risky situations, such as the presence of a predator. We tested responses to a visual predator cue (an owl silhouette) in male and female golden hamsters (Mesocricetus auratus). In a laboratory arena, there was no significant sex difference in the latency to enter the burrow or time spent in the burrow immediately after exposure to the owl silhouette. Males, however, were less likely to be active during the 3-min period following the animal’s exposure to the silhouette, indicating that male golden hamsters are more wary after exposure to an aerial predator cue than females. Most studies of responses to predators or predator cues have not considered sex differences, but our results show that males and females may have quite different responses to predator cues. Further work should be done to characterize and quantify sex differences in response to predators or predator cues.     

Evaluation of environmental conditions for production of bacteriocin-like substance by <Emphasis Type="Italic">Bacillus</Emphasis> sp. strain P34

The influence of temperature, pH and media on bacteriocin production by Bacillus sp. P34 was investigated. The effect of temperature and initial pH was evaluated by factorial design and response surface methodology (RSM). Statistical analysis of results showed that, in the range studied, the two variables have a significant effect on bacteriocin production. Response-surface data showed maximum antimicrobial activity production at initial pH values between 6.0 and 8.0 and temperatures between 25 and 37 °C. No relationship between bacterial growth and bacteriocin production was observed. RSM proved to be a powerful tool in optimizing the production of antimicrobial activity by Bacillus sp. P34. When different media were tested, maximum bacteriocin production was observed in soybean protein-based medium, but antimicrobial activity was not achieved by cultivation on fish meal, feather meal, whey and grape waste.     

Reproductive ecology of five pipefish species in one eelgrass meadow

Synopsis Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal care: only males aerate, osmoregulate and nourish the developing embryos. Two of the species (Entelurus aequoreus andNerophis ophidion) have simple ventral gluing of eggs on the trunk while three species (Syngnathus acus, S. rostellatus andS. typhle) have fully enclosed brood pouches on their tails. Males of the former species receive eggs from one female while males of the genusSyngnathus receive partial clutches from several females. Sex ratios of adults on the site differed from equal to male-biased to female-biased, according to species.S. typhle were most numerous and were resighted most often. They were present throughout the breeding season whereas there were temporal shifts in the presence of the other species on the meadow and in some sex ratios. Most species occurred in the deeper, denser part of the meadow but there was some habitat separation by species and sex. All species tended to stay low in the eelgrass, primarily coming up above the eelgrass to display and mate. No species showed site fidelity either to a home range or to the meadow, withE. aequoreus adults spending least time on the meadow. Sexual size dimorphism differed: males were larger inS. rostellatus, the same size inS acus and smaller in the other species. Although the species overlap in habitat requirements and breeding season, the only observed interspecific interactions were abortive courtships betweenSyngnathus species.     

Conformational Analysis of Isolated Domains of Helicobacter pylori CagA

The CagA protein of Helicobacter pylori is associated with increased virulence and gastric cancer risk. CagA is translocated into the host cell by a H. pylori type IV secretion system via mechanisms that are poorly understood. Translocated CagA interacts with numerous host factors, altering a variety of host signalling pathways. The recently determined crystal structure of C-terminally-truncated CagA indicated the presence of two domains: the smaller, flexible N-terminal domain and the larger, middle domain. In this study, we have investigated the conformation, oligomeric state and stability of the N-terminal, middle and glutamate-proline-isoleucine-tyrosine-alanine (EPIYA)-repeats domains. All three domains are monomeric, suggesting that the multimerisation of CagA observed in infected cells is likely to be mediated not by CagA itself but by its interacting partners. The middle and the C-terminal domains, but not the N-terminal domain, are capable of refolding spontaneously upon heat denaturation, lending support to the hypothesis that unfolded CagA is threaded C-terminus first through the type IV secretion channel with its N-terminal domain, which likely requires interactions with other domains to refold, being threaded last. Our findings also revealed that the C-terminal EPIYA-repeats domain of CagA exists in an intrinsically disordered premolten globule state with regions in PPII conformation - a feature that is shared by many scaffold proteins that bind multiple protein components of signalling pathways. Taken together, these results provide a deeper understanding of the physicochemical properties of CagA that underpin its complex cellular and oncogenic functions.