Spatial dependence and determinants of conservation easement adoptions in the United States.

A conservation easement is a market-based instrument for environmental protection. It has achieved rapid growth in the United States over the past few decades. As of 2015, 1.75% of the country's total land was placed under the restriction of conservation easements. In this study, spatial dependence in adopting conservation easements in the United States and the underlying determinants are examined through a spatial econometric model. The spatial panel data covers 50 individual states and six five-year intervals from 1990 to 2015. The findings reveal that spatial correlation in adopting conservation easements across individual states has become stronger over the study period, and the indirect spillover effect for most covariates is as high as one-third of the total effect. In addition, conservation easements have been utilized to protect threatened or strained natural resources. Populations with higher income or better education generally have helped the development of conservation easements. Government programs and policies favoring conservation easements also have positive impacts on easement adoption. These results can aid policymakers, landowners, and easement holders to efficiently allocate resources in acquiring conservation easements and managing currently eased land.

Hypertensive diseases in pregnancy, cardiac structure and function later in life: Insights from the Genetic Epidemiology Network of Arteriopathy (GENOA) study.

BACKGROUND: Hypertensive diseases in pregnancy have been associated with altered cardiac structure and function, yet these associations have not been systematically investigated in larger populations including African Americans. We evaluated the relationships between hypertensive diseases in pregnancy with cardiac structure and function later in life in the Genetic Epidemiology Network of Arteriopathy (GENOA) study. METHODS: We investigated 1013 African American women sibships with echocardiographic measurements from the GENOA study (Phase II, 2000-05; Jackson, MS). Women were classified as self-reported nulliparous (n = 61), a history of normotensive pregnancies (n = 780), a history of a hypertensive pregnancies (n = 152), or a history of preeclampsia (n = 20). We compared adjusted associations among these 4 groups with echocardiographic measurements of cardiac structure and function using generalized estimating equations, accounting for familial clustering. RESULTS: Among 1013 women with echocardiographic data (mean age 62 ± 9.5 years), women with a history of hypertensive pregnancy had lower left ventricular ejection fraction (LVEF) (P = 0.043) compared to nulliparous women and higher left atrial systolic dimension (LASD) compared to women with a history of normotensive pregnancies (P = 0.010), After adjusting for cardiovascular risk factors. There were no statistically significant differences in other echocardiographic parameters among these groups. CONCLUSIONS: A history of hypertension in pregnancy is associated with lower LVEF later in life, compared to nulliparous women and higher LASD compared to women with a history of normotensive pregnancies. However, given the multiple comparisons considered, this finding should be interpreted cautiously and requires further study.

Iron modulation of erythropoiesis is associated with Scribble-mediated control of the erythropoietin receptor.

Iron-restricted human anemias are associated with the acquisition of marrow resistance to the hematopoietic cytokine erythropoietin (Epo). Regulation of Epo responsiveness by iron availability serves as the basis for intravenous iron therapy in anemias of chronic disease. Epo engagement of its receptor normally promotes survival, proliferation, and differentiation of erythroid progenitors. However, Epo resistance caused by iron restriction selectively impairs proliferation and differentiation while preserving viability. Our results reveal that iron restriction limits surface display of Epo receptor in primary progenitors and that mice with enforced surface retention of the receptor fail to develop anemia with iron deprivation. A mechanistic pathway is identified in which erythroid iron restriction down-regulates a receptor control element, Scribble, through the mediation of the iron-sensing transferrin receptor 2. Scribble deficiency reduces surface expression of Epo receptor but selectively retains survival signaling via Akt. This mechanism integrates nutrient sensing with receptor function to permit modulation of progenitor expansion without compromising survival.

A specialized pathway for erythroid iron delivery through lysosomal trafficking of transferrin receptor 2.

Erythroid progenitors are the largest consumers of iron in the human body. In these cells, a high flux of iron must reach the mitochondrial matrix to form sufficient heme to support hemoglobinization. Canonical erythroid iron trafficking occurs via the first transferrin receptor (TfR1)-mediated endocytosis of diferric-transferrin into recycling endosomes, where ferric iron is released, reduced, and exported to the cytosol via DMT1. However, mice lacking TfR1 or DMT1 demonstrate residual erythropoiesis, suggesting additional pathways for iron use. How iron moves from endosomes to mitochondria is incompletely understood, with both cytosolic chaperoning and "kiss and run" interorganelle transfer implicated. TfR2, in contrast to its paralog TfR1, has established roles in iron sensing, but not iron uptake. Recently, mice with marrow-selective TfR2 deficiency were found to exhibit microcytosis, suggesting TfR2 may also contribute to erythroid hemoglobinization. In this study, we identify alternative trafficking, in which TfR2 mediates lysosomal transferrin delivery. Imaging studies reveal an erythroid lineage-specific organelle arrangement consisting of a focal lysosomal cluster surrounded by a nest of mitochondria, with direct contacts between these 2 organelles. Erythroid TfR2 deficiency yields aberrant mitochondrial morphology, implicating TfR2-dependent transferrin trafficking in mitochondrial maintenance. Human TFR2 shares a lineage- and stage-specific expression pattern with MCOLN1, encoding a lysosomal iron channel, and MFN2, encoding a protein mediating organelle contacts. Functional studies reveal these latter factors to be involved in mitochondrial regulation and erythroid differentiation, with Mfn2 required for mitochondrial-lysosomal contacts. These findings identify a new pathway for erythroid iron trafficking involving TfR2-mediated lysosomal delivery followed by interorganelle transfer to mitochondria.