Evidence That Two ATP-Dependent (Lon) Proteases in Borrelia burgdorferi Serve Different Functions

The canonical ATP-dependent protease Lon participates in an assortment of biological processes in bacteria, including the catalysis of damaged or senescent proteins and short-lived regulatory proteins. Borrelia spirochetes are unusual in that they code for two putative ATP-dependent Lon homologs, Lon-1 and Lon-2. Borrelia burgdorferi, the etiologic agent of Lyme disease, is transmitted through the blood feeding of Ixodes ticks. Previous work in our laboratory reported that B. burgdorferi lon-1 is upregulated transcriptionally by exposure to blood in vitro, while lon-2 is not. Because blood induction of Lon-1 may be of importance in the regulation of virulence factors critical for spirochete transmission, the clarification of functional roles for these two proteases in B. burgdorferi was the object of this study. On the chromosome, lon-2 is immediately downstream of ATP-dependent proteases clpP and clpX, an arrangement identical to that of lon of Escherichia coli. Phylogenetic analysis revealed that Lon-1 and Lon-2 cluster separately due to differences in the NH2-terminal substrate binding domains that may reflect differences in substrate specificity. Recombinant Lon-1 manifested properties of an ATP-dependent chaperone-protease in vitro but did not complement an E. coli Lon mutant, while Lon-2 corrected two characteristic Lon-mutant phenotypes. We conclude that B. burgdorferi Lons -1 and -2 have distinct functional roles. Lon-2 functions in a manner consistent with canonical Lon, engaged in cellular homeostasis. Lon-1, by virtue of its blood induction, and as a unique feature of the Borreliae, may be important in host adaptation from the arthropod to a warm-blooded host

Improving emotional availability in Australian mother-toddler dyads via the Tuning in to Toddlers parenting program

This study examined whether an emotion socialisation parenting program, Tuning in to Toddlers (TOTS), contributed to observed improvements in mother-toddler emotional availability. Parents of toddlers aged 18-36 months were recruited through childcare centres and maternal child health centres in Melbourne, Australia and were allocated to either an intervention or a waitlist control condition in a cluster-randomised controlled design. Parents in the intervention condition participated in 6 group sessions of TOTS. Baseline and 12-month follow up observation assessments for 99 mother-toddler dyads (intervention, n = 50; control, n = 49) were coded using the Emotional Availability Scales (4th edition) and analysed for between-group differences and clinically reliable change. Compared with the control condition, mothers in the intervention condition showed significant improvements in maternal sensitivity (p = 0.004). Further, significantly more intervention dyads reliably improved on maternal structuring (p =0 .013) and child responsiveness (p =0 .042), whereas those who received no intervention reliably deteriorated on maternal sensitivity (p = 0.001) and non-intrusiveness (p = 0.040). Thus, the preliminary evidence from this study indicates that an emotion socialisation program delivered to parents of toddlers may influence emotional availability