Multiple signaling systems target a core set of transition metal homeostasis genes using similar binding motifs.

Bacterial response to metals can require complex regulation. We report an overlapping regulation for copper and zinc resistance genes in the denitrifying bacterium, Pseudomonas stutzeri RCH2, by three two-component regulatory proteins CopR1, CopR2 and CzcR. We conducted genome-wide evaluations to identify gene targets of two paralogous regulators, CopR1 and CopR2, annotated for copper signaling, and compared the results with the gene targets for CzcR, implicated in zinc signaling. We discovered that the CopRs and CzcR have largely common targets, and crossregulate a core set of P. stutzeri copper and zinc responsive genes. We established that this crossregulation is enabled by a conserved binding motif in the upstream regulatory regions of the target genes. The crossregulation is physiologically relevant as these regulators synergistically and antagonistically target multicopper oxidases, metal efflux and sequestration systems. CopR1 and CopR2 upregulate two cop operons encoding copper tolerance genes, while all three regulators downregulate a putative copper chaperone, Psest_1595. CzcR also upregulated the oprD gene and the CzcIABC Zn2+ efflux system, while CopR1 and CopR2 downregulated these genes. Our study suggests that crossregulation of copper and zinc homeostasis can be advantageous, and in P. stutzeri this is enabled by shared binding motifs for multiple response regulators.

Ingestion of Lantana camara is not associated with significant effects in children.

OBJECTIVE: We sought to identify characteristics of children with reported ingestion of Lantana camara. METHODS: We reviewed the California Poison Control System database for all reported pediatric ingestions of L. camara for the years 1997-2008. Data collected included age, gender, clinical effects, duration of effects, medical interventions, and outcomes. RESULTS: There were a total of 641 patients; patient ages ranged from 1 to 16 years, with a mean of 2.5 years. Reported effects included vomiting (n = 30), abdominal pain (n = 8), agitation (n = 6), diarrhea (n = 6), throat/mouth irritation (n = 5), tachycardia (n = 4), drowsiness (n = 3), nausea (n = 2), and mydriasis (n = 1). There was no difference in frequency of symptoms between patients who ingested ripe (15.5% [95% confidence interval: 9.1%-21.8%]) versus unripe (6.0% [95% confidence interval: 0.9%-11.1%]) berries or between patients who ingested berries (10.5% [95% confidence interval: 7.3%-13.8%]) versus other plant parts (7.1% [95% confidence interval: 4.0%-10.3%]). Fifty-one patients (8%) were treated in a health care facility and 2 (0.3%) were admitted. No significant effects and no deaths were recorded. CONCLUSIONS: Ingestion of L. camara (including unripe berries) was not associated with significant toxicity; patients who ingested unripe berries did not exhibit more-frequent or more-severe symptoms than did patients who ingested ripe berries or other plant parts. Most patients displayed no or minimal symptoms. Children with asymptomatic ingestions and those with mild symptoms can be treated at home.