We isolated and characterized a pathogenicity-related protein in Salmonella enterica serovar Enteritidis (SE) from poultry farms, and designated it as SEp22, which has recently been identified with Salmonella Dps, a DNA-binding protein (12, 13, Amano et al., manuscript in preparation). Expression of SEp22 was shown to be transcriptionally regulated, because another SE strain without virulence was found to possess a full-length non-mutated gene of sep22, but had little expression of SEp22 mRNA and much lower levels of SEp22 protein compared to the virulent standard strain SE Cl#15-1. Besides, expression of SEp22 was connected with bacterial growth, showing reduced expression in the logarithmic phase but increased expression from the late logarithmic to stationary phases. These changes were slightly later than those in σ 38 levels as well as SEp22 mRNA, suggesting that expression of SEp22 is under transcriptional control through RNA polymerase activity by σ 38 . In addition, high levels of SEp22 in the stationary phase were rapidly reduced upon incubation of the bacteria in fresh medium. This reduction was dependent on bacterial concentration in the culture, temperature, and time of incubation, suggesting proteolytic degradation of SEp22 in growing bacteria.
SEp22, identical to Salmonella Dps, is a pathogenicity-related protein which we have isolated from the virulent Salmonella enterica subsp. enterica serovar Enteritidis (SE) from poultry farms. SEp22 is produced at the stationary phase, and rapidly lost upon incubation in fresh medium in vitro 1). In this study, we examined the effects of nutrients in the medium on the regulation of SEp22 expression. While Luria-Bertani (LB) medium induced the production of a large amount of SEp22 during culture overnight, M9 minimal medium had little or no effect. Addition of LB to M9 dose-dependently increased the amount of SEp22 produced, showing the requirement of certain nutrients in LB medium for the induction. It also suggests that simply entering the stationary phase from a growth phase is insufficient for the expression of SEp22 in a nutrient-poor medium like M9, contrary to the induction of Dps in nutritionally starved Escherichia coli (E. coli). A similar requirement of LB nutrients was observed during the rapid production of SEp22 in a logarithmic phase of growth in Salmonella treated with H2O2. On the other hand, no difference was observed between M9 and LB medium in the effect to decrease the amount of SEp22 accumulated during reincubation. These results show the importance of culture nutrients not in the breakdown but in inducing the expression of SEp22 in pathogenic SE.
Oral infection of serovar Enteritidis (SE) strains, SE # , SE # , and SE # , isolated from poultry farms was performed with specific pathogen-free (SPF) -day-old chicks and weeks-old BALB/c mice. SE # showed the strongest lethality to both chicks and mice, and SE # or # showed no e ects on the survival of mice, while SE # showed little and SE # intermediate lethal e ects to chicks. Using reverse transcriptation-PCR (RT-PCR), expression of pathogenic genes in these SE clones was examined; flagella ( ), invading host cell ( ), enterotoxin ( ) and DNA-binding protein from starved cells of ( ) genes were expressed in SE # and SE # , whereas was negative in SE # . However was more weakly expressed in SE # and SE # than SE # . Western blot analysis of total protein extracts of these SE strains revealed that SE # expressed highest levels of SEp , while SE # and SE # , significantly lower levels of this protein than SE# . This study showed the extents of expression at mRNA as well as protein level correlated well with pathogenicity of SE clones to chicks and mice, and these results suggest that SEp is a new virulence factor in both chick and mouse.
<p>In recent years, due to global climate change, flood disaster has become more frequent and intense. Along with this, many researchers in different fields are working on researches to reduce the damage caused by these severe water-related disasters. This study focusses on weather radars, which are mainly used for a countermeasure against flood damage in Japan. Our purpose is to examine the validity of weather radars currently set such as X band multi-parameter radars and C band radars in flood disasters which may cause serious damage in Japan.</p><p>The targeted flood disaster is one of the largest water-related disasters which caused severe damages to Japan, the typhoon Hagibis in 2019. It caused floods in more than 140 rivers. We used the observed data from weather radars of Chikuma and Abukuma river which are severely damaged in this disaster. Also, the Tama River in the Tokyo metropolitan area was flooded because of the heavy rainfall caused by Hagibis. we compared the accuracy of the multi-parameter radar and the single-parameter radar. thus, the issues of the current weather radar were extracted.</p><p>As a result, the accumulated rainfall of the single-parameter radars was larger than that of the multi-parameter radars. This may cause by the fact that radio wave of the multi-parameter radars will get attenuated when it passesthrough areas with strong rainfall so that it is difficult to observe some area if there is strong rainfall area between the radar and targeted area. In addition, the values observed by multi-parameter weather radars are fitted with the values by the ground rain gauges.</p><p>In conclusion, it was found that the multi-parameter weather radars have better accuracy of precipitation observation than that of the single parameter weather radars. Furthermore, it is necessary to consider the optimal position of multi-parameter weather radars to improve accuracy of the observation.</p>
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