Trophic interactions of the freshwater jellyfish Craspedacusta sowerbii

The predatory impact and the trophic role of the freshwaterjellyfish, Craspedacusta sowerbii, was studied using microcosmand enclosure experiments as well as a 3-year pond survey. Theresults showed a significant decrease of small herbivorous crustaceans,i.e. Bosmina longirostris and juvenile cyclopoid copepods, inthe medusa treatments of the microcosms and the enclosure experiments.Chlorophyll concentrations in the enclosure experiment weresignificantly increased in the medusa treatment, suggestingthat C. sowerbii may cause cascading effects in the food chain.A comparison of daily zooplankton losses during the pond surveycaused by medusae and fish (roach, Rutilus rutilus), and theirfood selectivities suggest food separation of these two predatorsand reveal a strong negative impact of medusae on the copepodpond community. In the case of a jellyfish bloom, our resultsshow that both food chains can co-occur in lakes because ofa weak interaction between these top predators, fish and jellyfish,with simultaneous impacts on the zooplankton structure.     

The sensitivity of<Emphasis Type="Italic">Escherichia coli</Emphasis> strains with K1 surface antigen and rods without this antigen to the bactericidal effect of serum

The susceptibility of Escherichia coli strains with K1 surface antigen (K1+) and rods without this antigen (K1-) to the bactericidal action of normal bovine serum and human normal cord serum was determined. Seventy E. coli strains (35 K1+ and 35 K1-) were isolated from urine obtained from children with urinary tract infections. The strains investigated showed variable sensitivity to the bactericidal action of the sera. E. coli K1+ strains were characterized by lower sensitivity to bactericidal effect of the sera in comparison with K1- rods. The role of the particular mechanisms of complement activation in the process of killing of the E. coli strains was also determined.     

Retention of the Gram-negative bacterium SW8 on surfaces under conditions relevant to the subsurface environment: Effects of conditioning films and substratum nature

Abstract Shallow (5–13 m) and deep (35–65 m) groundwaters were evaluated for their ability to generate conditioning films which affect bacterial adhesion to natural (sandstone, shale, andesite) and man-made substrata (polypropylene, stainless steel). Water contact angles indicated that all water samples produced conditioning films. Most films modified retention of the nonmotile Gram-negative bacterium SW8, but attachment of the organism did not correlate with water contact angles. Each borewater produced conditioning films with a characteristic attachment profile of SW8. Films adsorbed from standing borewaters often retained SW8 in different numbers than coatings derived from pumped bores. Groundwater chemistry was very heterogeneous and microbiological data indicated the presence of a diverse aerobic and anaerobic microbial community. These results indicate that conditioning films derived from dissolved compounds may play a significant role in controlling the interaction of bacteria with substrata in the subsurface.     

Quinolinic Aminoxyl Protects Albumin Against Peroxyl Radical Mediated Damage

A study of peroxyl radical-mediated bovine serum albumin oxidation in the presence of the quinolinic aminoxyl 1,2-dihydro-2,2-diphenyl-4-ethoxy-quinoline-1-oxyl (QAO) was carried out in order to test its efficiency as a protein antioxidant. Albumin oxidation was induced by the tert-butylhydroperoxide/PbO₂ system. The extent of protein oxidation, measured by monitoring the formation of carbonyl groups, was considerably reduced in the presence of QAO. ESR measurements were carried out to confirm the consumption of the nitroxide during oxidation and its incorporation in the protein. The data obtained indicate that the quinolinic aminoxyl function can be used as an effective antioxidant in biological systems.     

Influence of interactions between plasmids R. Vir and antigen K31 on the susceptibility of Escherichia coli strains to the normal rabbit serum

K31 antigen is the important element of outer membrane in resistance of E. coli H209 to the bactericidal activity of normal rabbit serum. The strains more resistant to the effect of serum are those containing simultaneously K31 and other factors, R plasmids (like R100. 1 and pAM588-Ia) or virulence plasmids (Vir). Mutant strains lacking of K31 antigen are strongly killed by the serum but this effect is delayed when these strains had one of the above plasmids.     

Bactericidal activity of human sera with a physiologic or genetic defect of the complement system

The serum of patient suffering genetically conditioned C2 defect showed a weak bactericidal activity against Pseudomonas aeruginosa strains. Out of 23 tested strains one was susceptible comparing with 16 ones sensitive to normal human serum. The normal cord serum exerted a bactericidal effect on 8 strains. All sera were found to be active against Salmonella strains tested.     

Blotting intact immunoglobulins and other high-molecular-weight proteins after composite agarose-polyacrylamide gel electrophoresis

A composite agarose-polyacrylamide gel containing urea and sodium dodecyl sulfate reliably resolved unreduced human immunoglobulins according to their molecular weight. Intact immunoglobulins and a number of other macromolecules were readily transferred to nitrocellulose paper by either capillary or electrophoretic blotting, although the latter technique was more effective. Conventional antigen probing as well as immobilized antibody studies can be performed on the nitrocellulose transfers.     

C55-Dolichol: occurrence in pig liver and preparation by hydrogenation of plant undecaprenol.

Apart from the long-chain dolichols (C80-C110), pig liver contains also a family of much shorter polyprenols with dominating C55-polyprenol. This compound was identified as cis/trans-dihydroundecaprenol in which the OH-terminal isoprene residue was saturated. The number of internal trans isoprene residues in this compound was three in comparison with two such residues in long-chain C95-dolichol. Chemical preparation of dihydroundecaprenol with a selectively saturated OH-terminal isoprene residue from fully unsaturated plant undecaprenol is presented.     

Inhibition of crossed caudal interneurons by lateral interneurons in lamprey spinal cord during fictive locomotion

Templates of the membrane potential profiles from lateral (LI) interneurons and motoneurons during glutamate- and N-methyl-D-aspartate (NMDA)-induced fictive locomotion showed pronounced plateau phases. In contrast, crossed caudal (CC) interneurons had a less obvious and steeper plateau region that was followed by a clear notch coinciding with the end of the lateral interneuron plateau phase. These results indicate a significant inhibitory input from LI to CC interneurons.