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.     

中国皿蛛科蜘蛛一新属和一新种记述(蛛形纲:蜘蛛目)

本文记述采自新疆的皿蛛科蜘蛛一新届——颚齿蛛属Maxillodens gen.nov.及其一新种——鞭状颚齿蛛M.flageuatus sp.nov。     

Sex behavior of male rats after gamma-irradiation: various radiobiological characteristics

The authors showed a pronounced and stable decrease in sexual motivation of male rats immediately after gamma-irradiation of the head with a dose of 2.58 C/kg. Exposure of the body to 1.29-2.58 C/kg radiation also inhibited sexual behaviour but only by the 45th-55th minute following irradiation: with higher doses some increase in sexual activity was observed immediately after irradiation.     

Two sequential phosphates 3' adjacent to the 8-oxoguanosine are crucial for lesion excision by E. coli Fpg protein and human 8-oxoguanine-DNA glycosylase

Escherichia coli formamidopyrimidine-DNA glycosylase (Fpg) and human 8-oxoguanine-DNA glycosylase (hOGG1) are base excision repair enzymes involved in the 8-oxoguanine (oxoG) repair pathway. Specific contacts between these enzymes and DNA phosphate groups play a significant role in DNA-protein interactions. To reveal the phosphates crucial for lesion excision by Fpg and hOGG1, modified DNA duplexes containing pyrophosphate and OEt-substituted pyrophosphate internucleotide (SPI) groups near the oxoG were tested as substrate analogues for both proteins. We have shown that Fpg and hOGG1 recognize and specifically bind the DNA duplexes tested. We have found that both enzymes were not able to excise the oxoG residue from DNA containing modified phosphates immediately 3' to the 8-oxoguanosine (oxodG) and one nucleotide 3' away from it. In contrast, they efficiently incised DNA duplexes bearing the same phosphate modifications 5' to the oxodG and two nucleotides 3' away from the lesion. The effect of these phosphate modifications on the substrate properties of oxoG-containing DNA duplexes is discussed. Non-cleavable oxoG-containing DNA duplexes bearing pyrophosphate or SPI groups immediately 3' to the oxodG or one nucleotide 3' away from it are specific inhibitors for both 8-oxoguanine-DNA glycosylases and can be used for structural studies of complexes comprising a wild-type enzymes bound to oxoG-containing DNA.     

Parallel phenotypic evolution in a wolf spider radiation on Galápagos

Within island archipelagos, repeated ecological settings may lead to radiations wherein similar niches are recurrently occupied. Although it has been shown that species with common habitat requirements share particular traits, it remains relatively unexplored to what extent this may lead to the repeated evolution of almost identical phenotypes (phenocopies) and how this correlates with traits subjected to sexual selection. Exploring divergence patterns of ecological and sexual relevant traits within spiders seem promising to enhance our understanding of the relative role of natural and sexual selection. Here, we conduct a detailed morphological analysis on a large set of genital and non‐genital traits (morphometrics, colour pattern) within a radiation of the wolf spider genus Hogna Simon, 1885 on Galápagos and interpret these data, taking into account their known phylogenetic relationship. Our results show that recurrent environmental gradients have led to the parallel evolution of almost identical phenotypes, which not only proves that natural selection has driven morphological divergence, but also suggests that a similar genetic or developmental basis most likely underlies this divergence. Among‐species variation in genital traits in contrast rather reflects the phylogenetic relationships on Santa Cruz and San Cristóbal. The combination of these data indicate that speciation in this system is driven by the combined effect of ecological mechanisms and allopatric divergence in sexual traits. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 123–136.     

Temporal variation in the genetic structure of host-associated populations of the small ermine moth Yponomeuta padellus (Lepidoptera, Yponomeutidae)

Temporal changes in allele frequencies were studied in host-associated populations of the small ermine moth Yponomeuta padellus. At one site, populations from three host plants (Sorbus aucuparia, Amelanchier larnarckii , and Crataegus spp.) were sampled annually during a four-year-period and analysed with 20 polymorphic allozyme markers. At two other sites, allele frequencies at 5- 6 enzyme loci of Y. padellus populations from two different host plants were also tested for consistency over a 13-year-pcriod. Significant allele frequency changes occurred in the short-term analysis, whereas allele frequencies remained relatively stable through time in the long-term analyses. Furthermore, allele frequencies of Y. padellus populations from Crataegus spp. were relatively stable compared to the other host populations. The role of the agents responsible for the observed patterns is discussed.     

Substance P and the ethanol-evoked changes in the independent motivated behavioral reactions of rabbits

Ethanol (0.5 g/kg) administered intravenously led to alterations in central mechanisms of feeding and escape, elicited by threshold electrical stimulation either of lateral or of ventromedial hypothalamic centers of the rabbit. Subsequent intravenous injection of substance P (30 mcg/kg) restored the excitability of the ventromedial hypothalamus and facilitatory effects on this motivational center of the midbrain reticular formation. The restoration of both inhibitory influences of the dorsal hippocampus and facilitatory ones of the midbrain reticular formation on the excitability of the lateral hypothalamus was also observed after SP administration. Data obtained suggest that oligopeptides could be used to increase the tolerance to ethanol or to cure the negative acute effects of alcohol in motivated behaviours.