We attempted to determine whether there is a limit to the transient, meal-induced decline in plasma zinc and whether there is a concomitant increase in erythrocyte and erythrocyte membrane concentrations. Premenopausal women participated in a 17-h fasting trial, a one-meal trial with breakfast at 0700, and a three-meal trial with meals at 0700, 0900, and 1100. During fasting, plasma zinc increased 9%; it decreased 11% and 19% in the one- and three-meal trials, respectively (P < 0.001). A limit to the decline in plasma zinc was reached after the second meal in the three-meal trial. Erythrocyte, erythrocyte membrane zinc, and serum calcium and phosphorus concentrations did not change significantly during the three trials. Serum glucose concentrations were weakly related to plasma zinc concentrations, suggesting that the postprandial decline in plasma zinc is associated with the metabolic changes caused by food intake.

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Municipal drinking water, regulated by the Environmental Protection Agency via the Safe Drinking Water act, has long been assumed to be contaminant-free. However, crises related to drinking water have emerged, most notably the “Flint Water Crisis” in Flint, MI, where high levels of lead (Pb) were detected in the area’s water. Much of the water-sampling data collected in Flint was obtained by “Citizen Scientists” working closely with a team of researchers at Virginia Tech, who used the analytical technique of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to quantify metal ions present in the water. Inspired by these efforts, we developed adaptable public water testing outreach efforts, led by students in Baltimore city (Middle School, High School, and College), to test the city’s drinking water. These “student-scientists” read news and scientific articles to understand the public health impact of lead in drinking water and the analytical approaches scientists use to detect metal ions in water. The students then developed a written “water collection protocol” and sought participation from colleagues (other students, faculty, and staff) who collected their home drinking water to be tested. The student scientists prepared and analyzed samples for lead (Pb) as well as copper (Cu), iron (Fe), and zinc (Zn) metal ions commonly found in drinking water, to be tested via ICP-MS. Data were then plotted onto a map of Baltimore City, with the metal levels indicated for each Zip code. This outreach event connects science to real-life news events while teaching analytical methodology and can be tailored to students at various stages of their education.

Cleavage and polyadenylation specificity factor 30 (CPSF30) is a 'zinc finger' protein that plays a crucial role in the transition of pre-mRNA to RNA. CPSF30 contains five conserved CCCH domains and a CCHC "Zinc Knuckle" domain. CPSF30 activity is critical for pre-mRNA processing. A truncated form of the protein, in which only the CCCH domains are present, has been shown to specifically bind AU-rich pre-mRNA targets; however, the RNA binding and recognition properties of full length CPSF30 are not known. Herein, we report the isolation and biochemical characterization of full length CPSF30. We report that CPSF30 contains one 2Fe-2S cluster in addition to five zinc ions, as measured by ICP-MS, UV-visible and XAS spectroscopies. Utilizing fluorescence anisotropy RNA binding assays, we show that full length CPSF30 has high binding affinity for two types of pre-mRNA targets -AAUAAA and poly U -both of which are conserved sequence motifs present in the majority of pre-mRNAs. Binding to the AAUAAA motif requires that the 5 CCCH domains of CPSF30 be present; whereas, binding to poly U sequences requires the entire, full length CPSF30. These findings implicate the CCHC "Zinc Knuckle" present in the full-length protein as critical for mediating poly U binding. We also report that truncated forms of the protein, containing either just two CCCH domains (ZF2 and ZF3) or the CCHC 'zinc knuckle' domain, do not exhibit any RNA binding, indicating that CPSF30/RNA binding requires several ZF (and/or Fe-S cluster) domains working in concert to mediate RNA recognition.