Characterisation of spontaneous behaviour in Göttingen minipigs in the home pen

Spontaneous behaviour in the home pen of group-housed minipigs was characterised with respect to social  interaction, activity, locomotion, exploration and resting behaviour. Sixteen adult male and female Göttingen minipigs were allocated in three groups. Data were acquired at  the age of seven and 16 months. Behaviour sampling was made by video recordings for two consecutive  days per group. The median values for initiating and receiving social contact were one to four times per individual during  30 min of observation in the main “activity period” (found to be 4 – 4.30 pm with the feeding regime) at  both ages; the variation between pigs was considerable. The animals spend a large amount of their active  time (during this time) exploring (76 %). During the six-hours resting period, three bouts of activity were  conspicuous in all three groups, and the highest level of activity was around midnight. The level of social  interaction at seven and 16 months of age did not differ significantly, and the social hierarchy of the pigs  in the three groups showed a high degree of consistency at seven and 16 months. However, correlation  analysis did not indicate a statistically significant relationship between the level of social interaction of the  individual pig at the young age and the older age. As relatively little is known about spontaneous behaviour of Göttingen minipigs this basal characterisation  of normal behaviour may serve as normative data for future studies of Göttingen minipig behaviour.

New Insights into <i>Staphylococcus aureus</i> Stress Tolerance and Virulence Regulation from an Analysis of the Role of the ClpP Protease in the Strains Newman, COL, and SA564

In <i>Staphylococcus aureus</i>, ClpP proteases were previously shown to be essential for virulence and stress tolerance in strains derived from NCTC8325. Because these strains exhibit a severely reduced activity of the alternative sigma factor, SigB, we here reassessed the role of ClpP in SigB-proficient clinical strains. To this end, <i>clpP</i> was deleted in strains COL, Newman, and SA564, and the strains were characterized phenotypically. The proteomic changes accomplished by the <i>clpP</i> deletion in the different strains were analyzed using the 2-D DIGE technique. The proteomic analyses revealed mostly conserved changes in the protein profiles of the ClpP-deficient strains. Among the strain-specific changes were the up-regulation of prophage proteins that coincided with an increased spontaneous release of prophages and the relatively poorer growth of the <i>clpP</i> mutants in some strain backgrounds. Interestingly, the effect of ClpP on the expression of selected virulence genes was strain-dependent despite the fact that the expression of the global virulence regulators RNAIII, <i>mgrA, sarZ</i>, <i>sarR</i>, and <i>arlRS</i> was similarly changed in all <i>clpP</i> mutants. ClpP affected the expression of <i>sarS</i> in a strain-dependent manner, and we propose that the differential expression of <i>sarS</i> is central to the strain-dependent effect of ClpP on the expression of virulence genes