Previous animal models of heat stress have been compromised by methodologies, such as restraint and anesthesia, that have confounded our understanding of the core temperature (T(c)) responses elicited by heat stress. Using biotelemetry, we developed a heat stress model to examine T(c) responses in conscious, unrestrained C57BL/6J male mice. Before heat stress, mice were acclimated for >4 wk to an ambient temperature (T(a)) of 25 degrees C. Mice were exposed to T(a) of 39.5 +/- 0.2 degrees C, in the absence of food and water, until they reached maximum T(c) of 42.4 (n = 11), 42.7 (n = 12), or 43.0 degrees C (n = 11), defined as mild, moderate, and extreme heat stress, respectively. Heat stress induced an approximately 13% body weight loss that did not differ by final group T(c); however, survival rate was affected by final T(c) (100% at 42.4 degrees C, 92% at 42.7 degrees C, and 46% at 43 degrees C). Hypothermia (T(c) < 34.5 degrees C) developed after heat stress, with the depth and duration of hypothermia significantly enhanced in the moderate and extreme compared with the mild group. Regardless of heat stress severity, every mouse that transitioned out of hypothermia (survivors only) developed a virtually identical elevation in T(c) the next day, but not night, compared with nonheated controls. To test the effect of the recovery T(a), a group of mice (n = 5) were acclimated for >4 wk and recovered at T(a) of 30 degrees C after moderate heat stress. Recovery at 30 degrees C resulted in 0% survival within approximately 2 h after cessation of heat stress. Using biotelemetry to monitor T(c) in the unrestrained mouse, we show that recovery from acute heat stress is associated with prolonged hypothermia followed by an elevation in daytime T(c) that is dependent on T(a). These thermoregulatory responses to heat stress are key biomarkers that may provide insight into heat stroke pathophysiology.

The hemochorial placenta develops from the coordinated multilineage differentiation of trophoblast stem (TS) cells. An invasive trophoblast cell lineage remodels uterine spiral arteries, facilitating nutrient flow, failure of which is associated with pathological conditions such as preeclampsia, intrauterine growth restriction, and preterm birth. Hypoxia plays an instructive role in influencing trophoblast cell differentiation and regulating placental organization. Key downstream hypoxia-activated events were delineated using rat TS cells and tested in vivo, using trophoblast-specific lentiviral gene delivery and genome editing. DNA microarray analyses performed on rat TS cells exposed to ambient or low oxygen and pregnant rats exposed to ambient or hypoxic conditions showed up-regulation of genes characteristic of an invasive/ vascular remodeling/inflammatory phenotype. Among the shared up-regulated genes was matrix metallopeptidase 12 (MMP12). To explore the functional importance of MMP12 in trophoblast celldirected spiral artery remodeling, we generated an Mmp12 mutant rat model using transcription activator-like nucleases-mediated genome editing. Homozygous mutant placentation sites showed decreased hypoxia-dependent endovascular trophoblast invasion and impaired trophoblast-directed spiral artery remodeling. A link was established between hypoxia/HIF and MMP12; however, evidence did not support Mmp12 as a direct target of HIF action. Lysine demethylase 3A (KDM3A) was identified as mediator of hypoxia/HIF regulation of Mmp12. Knockdown of KDM3A in rat TS cells inhibited the expression of a subset of the hypoxia-hypoxia inducible factor (HIF)-dependent transcripts, including Mmp12, altered H3K9 methylation status, and decreased hypoxia-induced trophoblast cell invasion in vitro and in vivo. The hypoxia-HIF-KDM3A-MMP12 regulatory circuit is conserved and facilitates placental adaptations to environmental challenges. placenta | hypoxia | trophoblast invasion | epigenetics | plasticity

Neonate movement and dispersal behavior of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), were investigated under controlled conditions on Bacillus thuringiensis (Bt) and non-Bt corn, Zea mays L., to assess plant abandonment, dispersal from their natal plant, and silking behavior after Bt and non-Bt preexposure. With continuous airflow, neonates on a Bt corn plant for 24 h abandoned that plant 1.78 times more frequently than neonates on a non-Bt corn plant. Indirect evidence indicated that at least one third of the neonates were capable of ballooning within 24 h. In the greenhouse, some neonates were recovered after 24 h from plants 76 and 152 cm away that likely ballooned from their natal plant. After 1 h of preexposure on a Bt corn leaf, neonates placed on a new corn leaf and observed for 10 min began silking off of a new Bt leaf significantly sooner than a new non-Bt leaf. Results suggest that neonates are unable to detect Bt in the corn within 10 min but that they can detect it within the first hour.

Epithelial barrier integrity is dependent on progenitor cells that either divide to replenish themselves or differentiate into a specialized epithelium. This paradigm exists in human placenta, where cytotrophoblast cells either propagate or undergo a unique differentiation program: fusion into an overlying syncytiotrophoblast. Syncytiotrophoblast is the primary barrier regulating the exchange of nutrients and gases between maternal and fetal blood and is the principal site for synthesizing hormones vital for human pregnancy. How trophoblast cells regulate their differentiation into a syncytium is not well understood. In this study, we show that the transcription factor OVO-like 1 (OVOL1), a homolog of Drosophila ovo, regulates the transition from progenitor to differentiated trophoblast cells. OVOL1 is expressed in human placenta and was robustly induced following stimulation of trophoblast differentiation. Disruption of OVOL1 abrogated cytotrophoblast fusion and inhibited the expression of a broad set of genes required for trophoblast cell fusion and hormonogenesis. OVOL1 was required to suppress genes that maintain cytotrophoblast cells in a progenitor state, including MYC, ID1, TP63, and ASCL2, and bound specifically to regions upstream of each of these genes. Our results reveal an important function of OVOL1 as a regulator of trophoblast progenitor cell fate during human trophoblast development.epithelial barrier | placenta | trophoblast | OVO-like 1 | differentiation E pithelial cells turn over regularly and are reliant on a pool of cells that either replenish the reservoir of progenitor cells or differentiate into the specialized epithelium required for that tissue's function. An excellent paradigm of epithelial turnover exists in the human placenta, where mononuclear cytotrophoblast cells lining the inner portion of the chorionic villi comprise the progenitor cells of the placental epithelium. These cells either propagate to maintain an adequate reservoir of progenitor cells or undergo a differentiation program that results in fusion with an overlying syncytium (1). This syncytium, termed "syncytiotrophoblast," forms the principal epithelial barrier separating maternal and fetal blood. Syncytiotrophoblast plays a vital role in regulating nutrient, water, waste, and gas exchange between maternal and fetal circulations and produces various hormones vital for fetal development and the maintenance of human pregnancy (2). Because of its importance for fetal health and development, disruptions in syncytiotrophoblast formation or functionality can have devastating consequences for pregnancy (3-5).Syncytiotrophoblast has a limited lifespan and is shed into the maternal circulation throughout pregnancy (6, 7). Therefore, to maintain the integrity of the maternal-fetal exchange surface, syncytiotrophoblast is continually replenished by select populations of cytotrophoblast cells that forego self-renewal and instead fuse into the overlying syncytiotrophoblast. This feature, analogous to paradigms established in othe...