Gestating at altitude: How do maternal physiology and evolutionary adaptation influence fetal growth?

Lowland mammals, including humans, experience an increased risk for fetal growth restriction (FGR) at high altitudes. FGR is associated with a range of adverse lifetime risks, including lower infant survival. Maternal physiology, such as cardiopulmonary function and nutrient provisioning, has been hypothesized to play an important role in driving altitude-dependent FGR, but strong associations between specific aspects of maternal physiology and FGR at altitude have been difficult to establish. One approach has been to study populations adapted to altitude; highland populations of humans, sheep, and deer mice (Peromyscus maniculatus) mitigate altitude-induced reductions in fetal growth and may thus offer insight into the relevant underlying physiology. We assessed the relationship between measures of maternal physiology and fetal growth outcomes using deer mice derived from highland-adapted and lowland populations that gestated under normoxia or hypobaric hypoxia. At late pregnancy, we measured fetal mass along with an array of physiological measures from dams (e.g., body and organ masses, and blood hematocrit and glucose). Using linear modeling, we assessed the relationships between maternal physiology and fetal growth phenotypes. To investigate the possibility that fetal growth is a function of many incremental changes in physiology, we compressed dimensionality of the maternal physiology data using PCA and then used the reduced dimensions in a linear modeling framework. The results from our study will add to our broader understanding of how maternal physiology shapes fetal growth, and they will help expand our understanding of the physiological systems that contribute to altitude adaptation across mammals

Fracture Sealing with Microbially-Induced Calcium Carbonate Precipitation: A Field Study

A primary environmental risk from unconventional oil and gas development or carbon sequestration is subsurface fluid leakage in the near wellbore environment. A potential solution to remediate leakage pathways is to promote microbially induced calcium carbonate precipitation (MICP) to plug fractures and reduce permeability in porous materials. The advantage of microbially induced calcium carbonate precipitation (MICP) over cement-based sealants is that the solutions used to promote MICP are aqueous. MICP solutions have low viscosities compared to cement, facilitating fluid transport into the formation. In this study, MICP was promoted in a fractured sandstone layer within the Fayette Sandstone Formation 340.8 m below ground surface using conventional oil field subsurface fluid delivery technologies (packer and bailer). After 24 urea/calcium solution and 6 microbial (Sporosarcina pasteurii) suspension injections, the injectivity was decreased (flow rate decreased from 1.9 to 0.47 L/min) and a reduction in the in-well pressure falloff (>30% before and 7% after treatment) was observed. In addition, during refracturing an increase in the fracture extension pressure was measured as compared to before MICP treatment. This study suggests MICP is a promising tool for sealing subsurface fractures in the near wellbore environment