The effect of cooling rate, freeze-drying suspending fluid and culture age on the preservation of Campylobacter pylori

The effects of freezing rate, suspending fluid and age of culture on the ability of four strains of Campylobacter pylori to survive and recover from freeze-drying were examined. Freeze-drying by standard procedures generally resulted in an overall loss in viability of between 3 and 7 log units. The exact cause of poor recovery by C. pylori was not established but strain differences were detected, with NCTC 11637 (type strain) surviving better than NCTC 11638 and NCTC 11639. Recovery of the poorest growing strain (NE 26695) was notably more erratic. The largest loss in viability occurred at the primary drying stage. Losses resulting from freezing and secondary drying were less marked and the rate of freezing had only a marginal effect on recovery. Nineteen different freeze-drying suspending fluids were investigated. Overall the best recovery results were obtained with 5% inositol-broth (or horse serum) plus 25% glucose, at pH 7.0, in which loss of viability was typically about 4 log units. Other factors, such as age of culture and number of viable bacteria in the before-dry suspension, did not have a significant effect on survival. We conclude from these results that C. pylori can survive freeze-drying, albeit in small numbers, but the degree of recovery is apparently largely strain dependent.     

Study of histamine binding to h2-receptors of gastric mucosa membranes of the frogRana ridibunda

The stability was studied of histamine H₂-receptors and of histamine-sensitive adenylyl cyclase of the crude membrane fraction of the gastric mucosa of the frogRana ridibunda to the action of exogenous hydrolases, lipase (phospholipase C), protease (papain), glycosidase (sialidase), and blockers of free SH-groups (iodoacetate and N-ethylmaleimide). The action of these agents on the free and histamine-occupied H₂ -receptors of the frog gastric mucosa was analyzed by the amount of the bound ligand. The histamine binding to receptor increased the receptor vulnerability to the effect of phospholipase C, papain, and SH-reagents. Study of the action of hydrolases on the basal and stimulated, histamine-sensitive adenylyl cyclase activity revealed that phospholipase C caused a decrease of the basal and all kinds of the stimulated activity of adenylyl cyclase, while papain and sialidase only prevented the histamine stimulation of the enzyme. The obtained data indicate changes of the surface exposure of functional groups during the specific ligand-receptor interaction.     

Age and Growth of the Black Scorpionfish Scorpaena porcus Linnaeus, 1758 (Scorpaeniformes: Scorpaenidae) under Anthropogenic Pressure in the Black Sea

Journal of Ichthyology - Age structure and growth dynamics are examined for the black scorpionfish Scorpaena porcus Linnaeus, 1758, from three sites characterized by different levels of pollution:...     

Neuronal activity in a honey bee (Apis mellifera L.) with kynurenine deficiency

Neuronal activity of the antennal lobes, mushroom bodies, and cervical connective in wild-type honey bees and snowlaranija mutants was recorded at different stages of the ontogeny (on the 1st, 3rd, 7th, and 25th days). The mutation snowlaranija affects the structural gene of tryptophane oxygenase, the first key exzyme in the kynurenine pathway of tryptophane metabolism, and leads to a deficit of kynurenines. Changes in neuronal activity in nutant bees were most pronounced in the cervical connective. A significant decrease in the pulse rate was revealed only in homozygous but not in heterozygous individuals. This finding is in accordance with previously reported inhibitory effect of the mutation at the behavioral level. Less pronounced effects were obtained when the neuronal activity was recorded in the antennal lobes or mushroom bodies. This may be related to a complex character of biochemical changes in different parts of mutants brain.     

Impact of Yersinia pseudotuberculosis on the in vitro production of cytokines by whole blood cells of donors

The impact of two plasmid (47, 82 MD), single plasmid (47 MD) and non plasmid Y. pseudotuberculosis strains, Y. enterocolitica (47 MD) as well as Y. pseudotuberculosis superantigen (YPM) on the production of interleukin-1 (IL-1), interleukin-6 (IL-6), interferon-alpha (IFN = alpha) and tumor necrosis factor alpha (TNF-alpha) by whole blood cells obtained from donors was studied. All Y. pseudotuberculosis and Y. enterocolitica strains stimulated the production of IFN-alpha, IL-1, IL-6 and TNF-alpha by whole blood cells, but considerably less than Y. pseudotuberculosis lipopolysaccharide and YPM. These data are indicative of the pathogenetic role played by 82 MD plasmid in manifestation of Y. pseudotuberculosis immunosuppressive properties. The maximum stimulation of the production of cytokines was observed under the action of YPM, which confirmed an important role played by this superantigen in the pathogenesis of Y. pseudotuberculosis.     

Hydraulic failure and tree dieback are associated with high wood density in a temperate forest under extreme drought

Catastrophic hydraulic failure will likely be an important mechanism contributing to large‐scale tree dieback caused by increased frequency and intensity of droughts under global climate change. To compare the susceptibility of 22 temperate deciduous tree and shrub species to hydraulic failure during a record drought in the southeastern USA, we quantified leaf desiccation, native embolism, wood density, stomatal conductance and predawn and midday leaf water potential at four sites with varying drought intensities. At the two driest sites, there was widespread leaf wilting and desiccation, and most species exhibited predawn leaf water potentials of ≤3 MPa and >60% loss of xylem conductivity in branches. Although species with high wood density were more resistant to cavitation, they had higher levels of native embolism and greater canopy dieback than species with low wood density. This unexpected result can be explained by the failure of species with dense wood to avert a decline in water potential to dangerous levels during the drought. Leaf water potential was negatively correlated with wood density, and the relationship was strongest under conditions of severe water deficit. Species with low wood density avoided catastrophic embolism by relying on an avoidance strategy that involves partial drought deciduousness, higher sensitivity of stomata to leaf water potential and perhaps greater rooting depth. These species therefore maintained water potential at levels that ensured a greater margin of safety against embolism. These differences among species may mediate rapid shifts in species composition of temperate forests if droughts intensify due to climate change.     

Amphibian and reptile biogeographic regions of Northern Eurasia,mapped separately

Distributions of amphibian and reptile faunas were separately delimited on a 1:20 000 000 vegetation map of Northern Eurasia divided into 245 10-degree-longitudinal segments of native subzone within the USSR borders as of 1990. All reptile and amphibian species recorded in every segment were listed, and the Jaccard indices were calculated, and the similarity matrix was studied with cluster analysis. Hierarchic classifications were made: the amphibian one consisting of 3 faunistic regions, divided into 4 subregions, 7 biologic provinces, and 23 districts. The reptile classification includes 4 faunistic regions, 7 subregions, 18 provinces, and 14 districts. The reptile classification has 1.5 times more provincial and district subdivisions than amphibian one. Environmental factors correlating with faunistic nonuniformity were revealed. Our amphibian and reptile schemes are 1.9 and 3.5 times more informative than those proposed earlier and account for 75 and 91% of variance in the faunal similarity coefficient of specific areas, respectively (multiple correlation coefficients 0.87 and 0.95). Environmental factors can explain 84 and 93% of faunistic nonuniformity (correlation coefficients 0.95 and 0.96).