The RNA Chaperone Hfq Is Important for Growth and Stress Tolerance in Francisella novicida

The RNA-binding protein Hfq is recognized as an important regulatory factor in a variety of cellular processes, including stress resistance and pathogenesis. Hfq has been shown in several bacteria to interact with small regulatory RNAs and act as a post-transcriptional regulator of mRNA stability and translation. Here we examined the impact of Hfq on growth, stress tolerance, and gene expression in the intracellular pathogen Francisella novicida. We present evidence of Hfq involvement in the ability of F. novicida to tolerate several cellular stresses, including heat-shock and oxidative stresses, and alterations in hfq gene expression under these conditions. Furthermore, expression of numerous genes, including several associated with virulence, is altered in a hfq mutant strain suggesting they are regulated directly or indirectly by Hfq. Strikingly, we observed a delayed entry into stationary phase and increased biofilm formation in the hfq mutant. Together, these data demonstrate a critical role for Hfq in F. novicida growth and survival

Mortality Rates in Poultry Species and Categories during Transport for Slaughter

Transport-related mortality rates were compared for various poultry species and categories where published data are limited. The numbers of broilers, hens and cockerels, turkeys, ducks, and geese transported for slaughter, and the numbers that died during such transport, were recorded from 1997 to 2006 in cooperation with the State Veterinary Administration of the Czech Republic. The mortality rate for individual poultry species and categories was calculated overall, and was also recorded for the following transport distances: up to 50 km, from 51 km to 100 km, from 101 km to 200 km, from 201 km to 300 km, and over 300 km. Transport of poultry for slaughter was accompanied by varying mortality rates depending on poultry species and categories. The highest mortality rates occurred in hens and cockerels (1.013%), followed by turkeys (0.272%), broilers (0.253%), ducks (0.103%), and geese (0.056%). Differences among the mortality rates estimated were highly significant (p < 0.001). Mortality rates highly correlated with transport distance. The lowest mortality rates were for the shortest transport distances: In broilers (0.154%), turkeys (0.164%), and hens and cockerels (0.595%) for a transport distance up to 50 km; and in ducks (0.069-0.111%) and geese (0.021 - 0.053%) for transport distances up to 300 km. Highest mortality rates in hens and cockerels (1.892%), turkeys (0.341%), and broilers (0.536%) were observed for transport distances over 200 km, while in ducks (0.147%) and geese (0.253%), highest mortality rates were with transport distances exceeding 300 km. The highest mortality rates for all transport distances were in hens and cockerels, followed by turkeys and broilers. The mortality rate in turkeys for a transport distance up to 50 km was significantly higher than that in broilers. No significant differences were found between mortality rates in turkeys and broilers for transport distances of 51-100 km and 101-200 km whereas, for a distance of 201-300 km and in distances exceeding 300 km, the mortality rates in broilers were significantly higher compared to turkeys. The lowest mortality rates were observed in ducks and geese, with a significant difference between them only for transport distances of 51 to 100 km, where the mortality rate in ducks was higher, and over 300 km, where the mortality rate in geese was higher. When planning the transport of poultry for slaughter, susceptibility to stress induced by transport and transport distance (i.e. the duration of transport) of poultry species and categories should be considered

Structural and Biochemical Studies on ATP Binding and Hydrolysis by the Escherichia coli RNA Chaperone Hfq

In Escherichia coli the RNA chaperone Hfq is involved in riboregulation by assisting base-pairing between small regulatory RNAs (sRNAs) and mRNA targets. Several structural and biochemical studies revealed RNA binding sites on either surface of the donut shaped Hfq-hexamer. Whereas sRNAs are believed to contact preferentially the YKH motifs present on the proximal site, poly(A)15 and ADP were shown to bind to tripartite binding motifs (ARE) circularly positioned on the distal site. Hfq has been reported to bind and to hydrolyze ATP. Here, we present the crystal structure of a C-terminally truncated variant of E. coli Hfq (Hfq65) in complex with ATP, showing that it binds to the distal R-sites. In addition, we revisited the reported ATPase activity of full length Hfq purified to homogeneity. At variance with previous reports, no ATPase activity was observed for Hfq. In addition, FRET assays neither indicated an impact of ATP on annealing of two model oligoribonucleotides nor did the presence of ATP induce strand displacement. Moreover, ATP did not lead to destabilization of binary and ternary Hfq-RNA complexes, unless a vast stoichiometric excess of ATP was used. Taken together, these studies strongly suggest that ATP is dispensable for and does not interfere with Hfq-mediated RNA transactions