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Ammonia metabolism is important in multiple aspects of gastrointestinal physiology, but the mechanisms of ammonia transport in the gastrointestinal tract remain incompletely defined. The present study examines expression of the ammonia transporter family members Rh B glycoprotein (RhBG) and Rh C glycoprotein (RhCG) in the mouse gastrointestinal tract. Real-time RT-PCR amplification and immunoblot analysis identified mRNA and protein for both RhBG and RhCG were expressed in stomach, duodenum, jejunum, ileum, and colon. Immunohistochemistry showed organ and cell-specific expression of both RhBG and RhCG. In the stomach, both RhBG and RhCG were expressed in the fundus and forestomach, but not in the antrum. In the forestomach, RhBG was expressed by all nucleated squamous epithelial cells, whereas RhCG was expressed only in the stratum germinativum. In the fundus, RhBG and RhCG immunoreactivity was present in zymogenic cells but not in parietal or mucous cells. Furthermore, zymogenic cell RhBG and RhCG expression was polarized, with apical RhCG and basolateral RhBG immunoreactivity. In the duodenum, jejunum, ileum, and colon, RhBG and RhCG immunoreactivity was present in villous, but not in mucous or crypt cells. Similar to the fundic zymogenic cell, RhBG and RhCG expression in villous epithelial cells was polarized when apical RhCG and basolateral RhBG immunoreactivity was present. Thus the ammonia transporting proteins RhBG and RhCG exhibit cell-specific, axially heterogeneous, and polarized expression in the intestinal tract suggesting they function cooperatively to mediate gastrointestinal tract ammonia transport. ammonia; small intestine; large intestine

Natural resource development, both extractive (oil, gas, mining, and timber) and non‐extractive (tourism, real estate, outdoor recreation), has been found to negatively impact economic prosperity in rural America. One mechanism recently proposed for why this occurs is high levels of labor market concentration, or oligopsony. Oligopsony occurs when there are few employers within a labor market and can lead to suppressed wages and a power imbalance between employers and workers. In this paper, we test the moderating effect of labor market concentration on the relationship between natural resource development and per capita income and poverty in rural America from 2010 to 2016. By comparing results between extractive and non‐extractive development, as well as manufacturing, we show that labor market concentration attenuates the beneficial relationship observed at low levels of specialization in natural resources—particularly for extractive forms of development. Further, by finding no significant relationship between manufacturing specialization and economic prosperity, nor any moderating effect of labor market concentration in the case of manufacturing, we demonstrate that natural resource development and labor market concentration have a unique relationship with rural American economic prosperity. [ABSTRACT FROM AUTHOR]