Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operations.

Unconventional oil and gas (UOG) operations have the potential to increase air and water pollution in communities located near UOG operations. Every stage of UOG operation from well construction to extraction, operations, transportation, and distribution can lead to air and water contamination. Hundreds of chemicals are associated with the process of unconventional oil and natural gas production. In this work, we review the scientific literature providing evidence that adult and early life exposure to chemicals associated with UOG operations can result in adverse reproductive health and developmental effects in humans. Volatile organic compounds (VOCs) [including benzene, toluene, ethyl benzene, and xylene (BTEX) and formaldehyde] and heavy metals (including arsenic, cadmium and lead) are just a few of the known contributors to reduced air and water quality that pose a threat to human developmental and reproductive health. The developing fetus is particularly sensitive to environmental factors, which include air and water pollution. Research shows that there are critical windows of vulnerability during prenatal and early postnatal development, during which chemical exposures can cause potentially permanent damage to the growing embryo and fetus. Many of the air and water pollutants found near UOG operation sites are recognized as being developmental and reproductive toxicants; therefore there is a compelling need to increase our knowledge of the potential health consequences for adults, infants, and children from these chemicals through rapid and thorough health research investigation.

The Escherichia coli DinD protein modulates RecA activity by inhibiting postsynaptic RecA filaments.

Escherichia coli dinD is an SOS gene up-regulated in response to DNA damage. We find that the purified DinD protein is a novel inhibitor of RecA-mediated DNA strand exchange activities. Most modulators of RecA protein activity act by controlling the amount of RecA protein bound to single-stranded DNA by affecting either the loading of RecA protein onto DNA or the disassembly of RecA nucleoprotein filaments bound to single-stranded DNA. The DinD protein, however, acts postsynaptically to inhibit RecA during an on-going DNA strand exchange, likely through the disassembly of RecA filaments. DinD protein does not affect RecA single-stranded DNA filaments but efficiently disassembles RecA when bound to two or more DNA strands, effectively halting RecA-mediated branch migration. By utilizing a nonspecific duplex DNA-binding protein, YebG, we show that the DinD effect is not simply due to duplex DNA sequestration. We present a model suggesting that the negative effects of DinD protein are targeted to a specific conformational state of the RecA protein and discuss the potential role of DinD protein in the regulation of recombinational DNA repair.

Tetraspanin CD82 regulates S1PR1-mediated hematopoietic stem and progenitor cell mobilization.

Hematopoietic stem and progenitor cell (HSPC) mobilization into the blood occurs under normal physiological conditions and is stimulated in the clinic to enable the isolation of HSPCs for transplantation therapies. In the present study, we identify the tetraspanin CD82 as a novel regulator of HSPC mobilization. Using a global CD82 knockout (CD82KO) mouse, we measure enhanced HSPC mobilization after granulocyte-colony stimulating factor (G-CSF) or AMD3100 treatment, which we find is promoted by increased surface expression of the sphingosine 1-phosphate receptor 1 (S1PR1) on CD82KO HSPCs. Additionally, we identify a disruption in S1PR1 internalization in CD82-deficient HSPCs, suggesting that CD82 plays a critical role in S1PR1 surface regulation. Finally, combining AMD3100 and anti-CD82 treatments, we detect enhanced mobilization of mouse HSPCs and human CD34+ cells in animal models. Together, these data provide evidence that CD82 is an important regulator of HSPC mobilization and suggests exploiting the CD82 scaffold as a therapeutic target to enhance stem cell isolation.

Tetraspanin Scaffold Proteins Function as Key Regulators of Hematopoietic Stem Cells.

Hematopoietic stem and progenitor cells (HSPCs) are responsible for the development, maintenance, and regeneration of all the blood forming cells in the body, and as such, are critical for a number of patient therapies. For successful HSPC transplantation, stem cells must traffic through the blood and home to the bone marrow (BM) microenvironment or "niche," which is composed of soluble factors, matrix proteins, and supportive cells. HSPC adhesion to, and signaling with, cellular and extracellular components of the niche provide instructional cues to balance stem cell self-renewal and differentiation. In this review, we will explore the regulation of these stem cell properties with a focus on the tetraspanin family of membrane proteins. Tetraspanins are molecular scaffolds that uniquely function to distribute proteins into highly organized microdomains comprising adhesion, signaling, and adaptor proteins. As such, tetraspanins contribute to many aspects of cell physiology as mediators of cell adhesion, trafficking, and signaling. We will summarize the many reports that identify tetraspanins as markers of specific HSPC populations. Moreover, we will discuss the various studies establishing the functional importance of tetraspanins in the regulation of essential HSPC processes including quiescence, migration, and niche adhesion. When taken together, studies outlined in this review suggest that several tetraspanins may serve as potential targets to modulate HSPC interactions with the BM niche, ultimately impacting future HSPC therapies.

Preconceptional, Gestational, and Lactational Exposure to an Unconventional Oil and Gas Chemical Mixture Alters Energy Expenditure in Adult Female Mice.

Previous studies conducted in our laboratory have found altered adult health outcomes in animals with prenatal exposure to environmentally relevant levels of unconventional oil and gas (UOG) chemicals with endocrine-disrupting activity. This study aimed to examine potential metabolic health outcomes following a preconception, prenatal and postnatal exposure to a mixture of 23 UOG chemicals. Prior to mating and from gestation day 1 to postnatal day 21, C57BL/6J mice were developmentally exposed to a laboratory-created mixture of 23 UOG chemicals in maternal drinking water. Body composition, spontaneous activity, energy expenditure, and glucose tolerance were evaluated in 7-month-old female offspring. Neither body weight nor body composition differed in 7-month female mice. However, females exposed to 1.5 and 150 µg/kg/day UOG mix had lower total and resting energy expenditure within the dark cycle. In the light cycle, the 1,500 µg//kg/day group had lower total energy expenditure and the 1.5 µg/kg/day group had lower resting energy expenditure. Females exposed to the 150 µg/kg/day group had lower spontaneous activity in the dark cycle, and females exposed to the 1,500 µg/kg/day group had lower activity in the light cycle. This study reports for the first time that developmental exposure to a mixture of 23 UOG chemicals alters energy expenditure and spontaneous activity in adult female mice.

Developmental Exposure to a Mixture of Unconventional Oil and Gas Chemicals Increased Risk-Taking Behavior, Activity and Energy Expenditure in Aged Female Mice After a Metabolic Challenge.

Chemicals used in unconventional oil and gas (UOG) operations can act as endocrine disrupting chemicals and metabolic disruptors. Our lab has reported altered energy expenditure and activity in C57BL/6J mice that were preconceptionally, gestationally, and lactationally exposed via maternal drinking water to a laboratory-created mixture of 23 UOG chemicals from gestational day 1 to postnatal day 21 in 7-month-old female mice with no change in body composition. We hypothesized that allowing the mice to age and exposing them to a high fat, high sugar diet might reveal underlying changes in energy balance. To investigate whether aging and metabolic challenge would exacerbate this phenotype, these mice were aged to 12 months and given a high fat, high sugar diet (HFHSD) challenge. The short 3-day HFHSD challenge increased body weight and fasting blood glucose in all mice. Developmental exposure to the 23 UOG mixture was associated with increased activity and non-resting energy expenditure in the light cycle, increased exploratory behavior in the elevated plus maze test, and decreased sleep in 12 month female mice. Each of these effects was seen in the light cycle when mice are normally less active. Further studies are needed to better understand the behavioral changes observed after developmental exposure to UOG chemicals.

Systematic review of the association between oil and natural gas extraction processes and human reproduction.

This systematic review identified 45 original published research articles related to oil and gas extraction activities and human reproductive endpoints. Reproductive outcomes were categorized as [1] birth outcomes associated with maternal exposure, [2] semen quality, fertility, and birth outcomes associated with adult paternal exposure, [3] reproductive cancers, and [4] disruption of human sex steroid hormone receptors. The results indicate there is moderate evidence for an increased risk of preterm birth, miscarriage, birth defects, decreased semen quality, and prostate cancer. The quality of the evidence is low and/or inadequate for stillbirth, sex ratio, and birth outcomes associated with paternal exposure, and testicular cancer, female reproductive tract cancers, and breast cancer, and the evidence is inconsistent for an increased risk of low birth weight; therefore, no conclusions can be drawn for these health effects. There is ample evidence for disruption of the estrogen, androgen, and progesterone receptors by oil and gas chemicals, which provides a mechanistic rationale for how exposure to oil and gas activities may increase the health risks we have outlined. The results from this systematic review suggest there is a negative impact on human reproduction from exposure to oil and gas activities. Many of the 45 studies reviewed identified potential human health effects. Most of these studies focused on conventional oil and gas activities. Few studies have been conducted to evaluate the impact of unconventional oil and gas operations on human health. The impact of unconventional oil and gas activities may be greater than that of conventional activity, given that unconventional activities employ many of the same approaches and use dozens of known endocrine-disrupting chemicals in hydraulic fracturing.

Adverse Reproductive and Developmental Health Outcomes Following Prenatal Exposure to a Hydraulic Fracturing Chemical Mixture in Female C57Bl/6 Mice.

Unconventional oil and gas operations using hydraulic fracturing can contaminate surface and groundwater with endocrine-disrupting chemicals. We have previously shown that 23 of 24 commonly used hydraulic fracturing chemicals can activate or inhibit the estrogen, androgen, glucocorticoid, progesterone, and/or thyroid receptors in a human endometrial cancer cell reporter gene assay and that mixtures can behave synergistically, additively, or antagonistically on these receptors. In the current study, pregnant female C57Bl/6 dams were exposed to a mixture of 23 commonly used unconventional oil and gas chemicals at approximately 3, 30, 300, and 3000 µg/kg·d, flutamide at 50 mg/kg·d, or a 0.2% ethanol control vehicle via their drinking water from gestational day 11 through birth. This prenatal exposure to oil and gas operation chemicals suppressed pituitary hormone concentrations across experimental groups (prolactin, LH, FSH, and others), increased body weights, altered uterine and ovary weights, increased heart weights and collagen deposition, disrupted folliculogenesis, and other adverse health effects. This work suggests potential adverse developmental and reproductive health outcomes in humans and animals exposed to these oil and gas operation chemicals, with adverse outcomes observed even in the lowest dose group tested, equivalent to concentrations reported in drinking water sources. These endpoints suggest potential impacts on fertility, as previously observed in the male siblings, which require careful assessment in future studies.

Endocrine-Disrupting Activity of Hydraulic Fracturing Chemicals and Adverse Health Outcomes After Prenatal Exposure in Male Mice.

Oil and natural gas operations have been shown to contaminate surface and ground water with endocrine-disrupting chemicals. In the current study, we fill several gaps in our understanding of the potential environmental impacts related to this process. We measured the endocrine-disrupting activities of 24 chemicals used and/or produced by oil and gas operations for five nuclear receptors using a reporter gene assay in human endometrial cancer cells. We also quantified the concentration of 16 of these chemicals in oil and gas wastewater samples. Finally, we assessed reproductive and developmental outcomes in male C57BL/6J mice after the prenatal exposure to a mixture of these chemicals. We found that 23 commonly used oil and natural gas operation chemicals can activate or inhibit the estrogen, androgen, glucocorticoid, progesterone, and/or thyroid receptors, and mixtures of these chemicals can behave synergistically, additively, or antagonistically in vitro. Prenatal exposure to a mixture of 23 oil and gas operation chemicals at 3, 30, and 300 µg/kg · d caused decreased sperm counts and increased testes, body, heart, and thymus weights and increased serum testosterone in male mice, suggesting multiple organ system impacts. Our results suggest possible adverse developmental and reproductive health outcomes in humans and animals exposed to potential environmentally relevant levels of oil and gas operation chemicals.