A global reconnaissance of particulates and metals/metalloids in untreated drinking water sources.

Metal and metalloid contamination in drinking water sources is a global concern, particularly in developing countries. This study used hollow membrane water filters and metal-capturing polyurethane foams to sample 71 drinking water sources in 22 different countries. Field sampling was performed with sampling kits prepared in the lab at Hope College in Holland, MI, USA. Filters and foams were sent back to the lab after sampling, and subsequent analysis of flushates and rinsates allowed the estimation of suspended solids and metal and other analayte concentrations in source waters. Estimated particulate concentrations were 0-92 mg/L, and consisted of quartz, feldspar, and clay, with some samples containing metal oxides or sulfide phases. As and Cu were the only analytes which occurred above the World Health Organization (WHO) guidelines of 10 µg/L and 2000 µg/L, respectively, with As exceeding the guideline in 45% of the sources and Cu in 3%. Except for one value of ~ 285 µg/L, As concentrations were 45-200 µg/L (river), 65-179 µg/L (well), and 112-178 µg/L (tap). Other metals (Ce, Fe, Mg, Mn, Zn) with no WHO guideline were also detected, with Mn the most common. This study demonstrated that filters and foams can be used for reconnaissance characterization of untreated drinking water. However, estimated metal and other analyte concentrations could only be reported as minimum values due to potential incomplete retrieval of foam-bound analytes. A qualitative reporting methodology was used to report analytes as "present" if the concentration was below the WHO guideline, and "present-recommend retesting" if the concentration was quantifiable and above the WHO guideline.

Providing a Safe, In-Person, Residential College Experience During the COVID-19 Pandemic.

Due to the COVID-19 pandemic, higher education institutions were forced to make difficult decisions regarding the 2020-2021 academic year. Many institutions decided to have courses in an online remote format, others decided to attempt an in-person experience, while still others took a hybrid approach. Hope College (Holland, MI) decided that an in-person semester would be safer and more equitable for students. To achieve this at a residential college required broad collaboration across multiple stakeholders. Here, we share lessons learned and detail Hope College's model, including wastewater surveillance, comprehensive testing, contact tracing, and isolation procedures that allowed us to deliver on our commitment of an in-person, residential college experience.

Diarrhea prevalence in a randomized, controlled prospective trial of point-of-use water filters in homes and schools in the Dominican Republic.

BACKGROUND: Lack of sustainable access to clean drinking water continues to be an issue of paramount global importance, leading to millions of preventable deaths annually. Best practices for providing sustainable access to clean drinking water, however, remain unclear. Widespread installation of low-cost, in-home, point of use water filtration systems is a promising strategy. METHODS: We conducted a prospective, randomized, controlled trial whereby 16 villages were selected and randomly assigned to one of four treatment arms based on the installation location of Sawyer® PointONE™ filters (filter in both home and school; filter in home only; filter in school only; control group). Water samples and self-reported information on diarrhea were collected at multiple times throughout the study. RESULTS: Self-reported household prevalence of diarrhea decreased from 25.6 to 9.76% from installation to follow-up (at least 7 days, and up to 200 days post-filter installation). These declines were also observed in diarrhea with economic or educational consequences (diarrhea which led to medical treatment and/or missing school or work) with baseline prevalence of 9.64% declining to 1.57%. Decreases in diarrhea prevalence were observed across age groups. There was no evidence of a loss of efficacy of filters up to 200 days post-filter installation. Installation of filters in schools was not associated with decreases in diarrhea prevalence in school-aged children or family members. Unfiltered water samples both at schools and homes contained potential waterborne bacterial pathogens, dissolved heavy metals and metals associated with particulates. All dissolved metals were detected at levels below World Health Organization action guidelines. CONCLUSIONS: This controlled trial provides strong evidence of the effectiveness of point-of-use, hollow fiber membrane filters at reducing diarrhea from bacterial sources up to 200 days post-installation when installed in homes. No statistically significant reduction in diarrhea was found when filters were installed in schools. Further research is needed in order to explore filter efficacy and utilization after 200 days post-installation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03972618 . Registered 3 June 2019-retrospectively registered.

Substitution of DNA-contacting amino acids with functional variants in the Gata-1 zinc finger: a structurally and phylogenetically guided mutagenesis.

DNA-binding functionality among transcription factor proteins is afforded by a number of structural motifs, such as the helix-turn-helix, helix-loop-helix, and zinc finger domains. The common thread among these diverse structures is their sequence-specific binding to essential promoter or other genetic regulatory sequences with high selectivity and affinity. One such motif, present in a wide range of organisms from bacteria to vertebrates, is the Gata-type zinc finger. This family of DNA-binding proteins is characterized by the presence of one or two (Cys)(4) metal binding sites which recognize the protein's eponymous binding site, GATA. Unlike other conserved DNA-binding domains, Gata proteins appear to be restricted to binding consensus GATA sequences, or near variations, in DNA. Since the architecture of the Gata finger seems built around recognizing this particular sequence, we set out to define the allowable range of amino acid substitutions along the DNA-binding surface of a Gata finger that could continue to support sequence-specific DNA-binding activity. Accordingly, we set up a one-hybrid screen in yeast based on the chicken Gata-1 C-terminal zinc finger. Mutant libraries were generated at five amino acids identified in the Gata-DNA structure as likely to mediate sequence-specific contacts between the Gata finger and DNA. These libraries were designed to give as exhaustive amino acid coverage as possible such that almost all alternative amino acids were screened at each of the five probed positions. Screening and characterization of these libraries revealed several functional amino acid substitutions at two leucines which contact the DNA at the 3' and 5' flanks of the GATA binding site, but no functional substituents for amino acids near the core of the binding site. This pattern is consistent with amino acid sequences of known DNA-binding Gata fingers.

Spectroscopic and functional determination of the interaction of Pb2+ with GATA proteins.

GATA proteins are transcription factors that bind GATA DNA elements through Cys4 structural zinc-binding domains and play critical regulatory roles in neurological and urogenital development and the development of cardiac disease. To evaluate GATA proteins as potential targets for lead, spectroscopically monitored metal-binding titrations were used to measure the affinity of Pb2+ for the C-terminal zinc-binding domain from chicken GATA-1 (CF) and the double-finger domain from human GATA-1 (DF). Using this method, Pb2+ coordinating to CF and DF was directly observed through the appearance of intense bands in the near-ultraviolet region of the spectrum (250-380 nm). Absorption data collected from these experiments were best fit to a 1:1 Pb2+ -CF model and a 2:1 Pb2+ -DF model. Competition experiments using Zn2+ were used to determine the absolute affinities of Pb2+ for these proteins. These studies reveal that Pb2+ forms tight complexes with cysteine residues in the zinc-binding sites in GATA proteins, beta1Pb = 6.4 (+/- 2.0) x 10(9) M(-1) for CF and beta2 = 6.3 (+/- 6.3) x 10(19) M(-2) for Pb(2+)2-DF, and within an order of magnitude of the affinity of Zn2+ for these proteins. Furthermore, Pb2+ was able to displace bound Zn2+ from CF and DF. Upon addition of Pb2+, GATA shows a decreased ability to bind to DNA and subsequently activate transcription. Therefore, the DNA binding and transcriptional activity of GATA proteins are most likely to be targeted by Pb2+ in cells and tissues that sequester Pb2+ in vivo, which include the brain and the heart.

A molecular dissection of the interaction between the transcription factor Gata-1 zinc finger and DNA.

The production of circulating blood cells from bone marrow stem cells during hematopoiesis is accompanied by overall changes in gene expression which cause production of required functional proteins, such as hemoglobin in erythroid cells, as well as control of cell growth, preventing apoptosis of differentiating cells. Hematopoietic gene regulation is controlled by several specific transcription factors, including the factor Gata-1, which is required for erythrocyte maturation. Based on contacts observed in the NMR structure of the cGata-1 binding domain in complex with DNA, the protein's key DNA interface is interesting in being quite hydrophobic in nature, due to the presence of three leucine side chains protruding toward the DNA. Given the T-rich composition of the GATA DNA binding site, it is possible that thymine's unique 5-methyl group may mediate some of these hydrophobic contacts to increase the stability of binding. The hypothesis that thymine methyl groups are important to the free energy of binding between Gata and DNA is tested by measuring binding of an oligonucleotide substrate in which individual thymine bases are substituted with uracil. To test for any important base-pair specific interactions which may be hydrogen-bonded in character, we have also assayed Gata binding to oligonucleotides with base analogs which cannot make hydrogen bonds. We report that out of the binding site's five thymine methyl groups, only one appeared to make a notable contribution to binding affinity, with removal causing a loss of less than 1kcal/mol of binding free energy. On the other hand, perturbing the potential hydrogen-bonding surface of the DNAs major groove was found to cause a larger decrease in binding affinity than removal of any of the thymine methyl groups, with a loss of 2-3kcal/mol of binding free energy.

Position-effect protection and enhancer blocking by the chicken beta-globin insulator are separable activities.

The 1.2-kb DNA sequence element (5'HS4) at the 5' end of the chicken beta-globin locus has the two defining properties of an insulator: it prevents an "external" enhancer from acting on a promoter when placed between them ("enhancer blocking") and acts as a barrier to chromosomal position effect (CPE) when it surrounds a stably integrated reporter. We previously reported that a single CTCF-binding site in 5'HS4 is necessary and sufficient for enhancer blocking. We show here that a 250-bp "core" element from within 5'HS4 is sufficient to confer protection against silencing of transgenes caused by CPE. Further dissection of the core reveals that 5'HS4 is a compound element in which it is possible to separate enhancer blocking and barrier activities. We demonstrate that full protection against CPE is conferred by mutant 5'HS4 sequences from which the CTCF-binding site has been deleted. In contrast, mutations of four other protein binding sites within 5'HS4 result in varying reductions in the ability to protect against CPE. We find that binding sites for CTCF are neither necessary nor sufficient for protection against CPE. Comparison of the properties of 5'HS4 with those of other CTCF-binding enhancer-blocking elements suggests that CPE protection is associated with maintenance of a high level of histone acetylation near the insulator, conferred by insulator binding-proteins other than CTCF.