Family networks and household outcomes in an economic crisis

Thesis (Ph.D.)--Boston UniversityThis thesis theoretically and empirically analyzes the nature and consequences of interactions between family members. The first chapter tests whether children's human capital accumulation was significantly affected by earnings shocks to their nonresident kin in the context of the 1997-8 financial crisis in Indonesia. The crisis produced sudden, heterogeneous shocks that facilitate the construction of an exogenous measure of earnings changes. Results indicate that earnings shocks to nonresident kin - including extended family and relatives living in other districts- significantly affected children's human capital accumulation between 1997 and 2000, and ultimate educational attainment measured nearly a decade after the crisis hit. Supplementary results point to intra-family transfers, underpinned by ex post altruism, as an important channel of causation. The second chapter develops a theoretical model of private transfers underpinned by ex post altruism among members of a network. I use this model to analyze equilibrium transfer patterns and inequality under alternative income distributions and network structures. I demonstrate the general intuition that transfers obtain in equilibrium when the amount of altruism is sufficiently strong relative to income inequality. Within the networks that I analyze, every equilibrium involving transfers takes the same form: unique income thresholds separate senders from receivers. Effective risk sharing takes place among senders and receivers, while those at intermediate incomes remain in autarky. Every equilibrium gives rise to the same set of allocations. I contrast these predictions with insurance-based theories of transfers in which risk sharing is operative for small in come differences and may fall apart at large income differences. The third chapter uses longitudinal data spanning nearly fifteen years to test whether transfers among family members within Indonesia are consistent with ex post altruism, against the alternative of insurance. I use the predicted effects of permanent versus transitory income on transfers, as well as theoretical predictions from the second chapter regarding the shape of transfer functions , to carry out this test. The results provide some evidence that transfer motives are inconsistent with insurance but consistent with ex post altruism

Pathways of Carbon Assimilation and Ammonia Oxidation Suggested by Environmental Genomic Analyses of Marine Crenarchaeota

Marine Crenarchaeota represent an abundant component of oceanic microbiota with potential to significantly influence biogeochemical cycling in marine ecosystems. Prior studies using specific archaeal lipid biomarkers and isotopic analyses indicated that planktonic Crenarchaeota have the capacity for autotrophic growth, and more recent cultivation studies support an ammonia-based chemolithoautotrophic energy metabolism. We report here analysis of fosmid sequences derived from the uncultivated marine crenarchaeote, Cenarchaeum symbiosum, focused on the reconstruction of carbon and energy metabolism. Genes predicted to encode multiple components of a modified 3-hydroxypropionate cycle of autotrophic carbon assimilation were identified, consistent with utilization of carbon dioxide as a carbon source. Additionally, genes predicted to encode a near complete oxidative tricarboxylic acid cycle were also identified, consistent with the consumption of organic carbon and in the production of intermediates for amino acid and cofactor biosynthesis. Therefore, C. symbiosum has the potential to function either as a strict autotroph, or as a mixotroph utilizing both carbon dioxide and organic material as carbon sources. From the standpoint of energy metabolism, genes predicted to encode ammonia monooxygenase subunits, ammonia permease, urease, and urea transporters were identified, consistent with the use of reduced nitrogen compounds as energy sources fueling autotrophic metabolism. Homologues of these genes, recovered from ocean waters worldwide, demonstrate the conservation and ubiquity of crenarchaeal pathways for carbon assimilation and ammonia oxidation. These findings further substantiate the likely global metabolic importance of Crenarchaeota with respect to key steps in the biogeochemical transformation of carbon and nitrogen in marine ecosystems

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

Exercise capacity is a strong predictor of all-cause mortality. Skeletal muscle mitochondrial respiratory capacity, its biggest contributor, adapts robustly to changes in energy demands induced by contractile activity. While transcriptional regulation of mitochondrial enzymes has been extensively studied, there is limited information on how mitochondrial membrane lipids are regulated. Here, we show that exercise training or muscle disuse alters mitochondrial membrane phospholipids including phosphatidylethanolamine (PE). Addition of PE promoted, whereas removal of PE diminished, mitochondrial respiratory capacity. Unexpectedly, skeletal muscle–specific inhibition of mitochondria-autonomous synthesis of PE caused respiratory failure because of metabolic insults in the diaphragm muscle. While mitochondrial PE deficiency coincided with increased oxidative stress, neutralization of the latter did not rescue lethality. These findings highlight the previously underappreciated role of mitochondrial membrane phospholipids in dynamically controlling skeletal muscle energetics and function