Stratigraphic records of macroscopic charcoal particles (Ͼ125 m in diameter) are widely used as a means of reconstructing past fire events, yet fire-history studies rest on assumptions about the processes by which charcoal is transported and deposited in lake sediments. In order to clarify the interpretation of charcoal data, charcoal abundance in sediment cores was examined from 36 lakes within and near the 1996 Charlton Burn, a large stand-replacing fire in the central Cascade Range of Oregon. Stratigraphic variations in charcoal abundance provided strong evidence that macroscopic charcoal recorded a signal of local fire and that prevailing winds affected charcoal transportation, increasing charcoal abundance in lakes downwind of the fire. Charcoal abundance in the uppermost sediments (0-2 cm depth) was related primarily to whether or not a site had burned and secondarily to the surface area of the lake. At the Charlton Burn area, other variables that may influence the transportation of charcoal after a fire, such as relative position of unburned lakes, distance of the lake from the centre of the fire, maximum adjacent slope, and width of riparian vegetation, were not statistically significant. These results support the assumption in charcoal analysis that there is a relationship between the occurrence of local fire and peaks in macroscopic charcoal. Confirming this relationship strengthens the interpretation of long-term fire-history records.

Background: Gestational sleep apnea affects 8-26% of pregnancies and can increase the risk for autism spectrum disorder (ASD) in offspring. ASD is a neurodevelopmental disorder associated with social dysfunction, repetitive behaviors, anxiety, and cognitive impairment. To examine the relationship between gestational sleep apnea and ASD-associated behaviors, we used a chronic intermittent hypoxia (CIH) protocol between gestational days (GD) 15-19 in pregnant rats to model late gestational sleep apnea. We hypothesized that late gestational CIH would produce sex- and age-specific social, mood, and cognitive impairments in offspring. Methods: Timed pregnant Long-Evans rats were exposed to CIH or room air normoxia from GD 15-19. Behavioral testing of offspring occurred during either puberty or young adulthood. To examine ASD-associated phenotypes, we quantified ASD-associated behaviors (social function, repetitive behaviors, anxiety-like behaviors, and spatial memory and learning), hippocampal activity (glutamatergic NMDA receptors, dopamine transporter, monoamine oxidase-A, EGR-1, and doublecortin), and circulating hormones in offspring. Results: Late gestational CIH induced sex- and age-specific differences in social, repetitive and memory functions in offspring. These effects were mostly transient and present during puberty. In female pubertal offspring, CIH impaired social function, increased repetitive behaviors, and increased circulating corticosterone levels, but did not impact memory. In contrast, CIH transiently induced spatial memory dysfunction in pubertal male offspring but did not impact social or repetitive functions. Long-term effects of gestational CIH were only observed in female offspring, wherein CIH induced social disengagement and suppression of circulating corticosterone levels in young adulthood. No effects of gestational CIH were observed on anxiety-like behaviors, hippocampal activity, circulating testosterone levels, or circulating estradiol levels, regardless of sex or age of offspring. Conclusions: Our results indicate that hypoxia-associated pregnancy complications during late gestation can increase the risk for ASD-associated behavioral and physiological outcomes, such as pubertal social dysfunction, corticosterone dysregulation, and memory impairments.

Background Infections during pregnancy are associated with adverse maternal and fetal outcomes. We previously showed that exposure to immunostimulatory CpG oligonucleotides (ODN2395, synthetic Toll‐like receptor 9 agonist) during pregnancy induces maternal vascular inflammation and enhances vascular tone in pregnant rats. These outcomes were mediated in part by activation of the cyclooxygenase/thromboxane A2 (COX/TxA2) pathway. The objective of this study was to investigate the impact of ODN2395‐induced immune system stimulation on maternal hearts during pregnancy. Hypotheses Exposure to TLR9‐mediated immune system activation during pregnancy upregulates the COX/TxA2signaling pathway in maternal cardiac tissues. Methods Rats were treated with a synthetic CpG DNA (ODN2395, 1 mg/kg, intraperitoneal injection) or vehicle (saline) in late pregnancy (gestational day (GD) 14, 16, and 18) and euthanized on GD 20 (term 22‐23). Fetoplacental biometrics were recorded after euthanasia and maternal hearts were collected to assess COX‐1 and COX‐2 expression via western blotting and 6‐keto PGF1α (PGI2 metabolic byproduct) and TxB2 (TxA2 metabolic byproduct) production use ELISA. Results Maternal heart weights did not differ between groups (ODN2395: 0.26 g/100 g BW vs. Vehicle: 0.23 g/100 g BW, n≥7, p=0.11). Left ventricular tissues from dams treated with ODN2395 released higher concentrations of TxB2compared to cardiac tissues from vehicle‐treated dams (ODN2395: 0.56 ± 0.06 ng/mg total protein vs. Vehicle: 0.31 ± 0.04 ng/mg total protein, n≥5, p=0.0041) but there were no differences in cardiac 6‐keto PGF1α release between groups (p=0.16). COX‐2 expression was lower in left ventricles from ODN2395‐treated rats compared to vehicle‐treated rats (p=0.009). There were no differences in cardiac COX‐1 expression between groups (p=0.27). Exposure to ODN2395 during pregnancy did not affect fetal weights (ODN2395: 2.28 ± 0.03 g vs. Vehicle: 2.25 ± 0.06 g, n≥7, p=0.9) or placenta weights (ODN2395: 0.44 ± 0.02 g vs. Vehicle 0.49 ± 0.01 g, n≥7, p=0.06), but increased fetal‐placental weight ratio (ODN2395: 5.3 ± 0.22 vs. Vehicle: 4.7 ± 0.15, p = 0.04). COX‐2 expression was greater in placental tissues from ODN2395‐treated rats (p=0.004) but there were no differences in placental 6‐keto PGF1α(p=0.51) and TxB2 production (p=0.32). Conclusion Exposure to immunostimulatory CpG ODN during pregnancy induces upregulation of TxB2 synthesis in maternal cardiac tissues coupled with a reduction in COX‐2 expression. We suggest that cardiac inflammation during pregnancy may increase maternal risk for future cardiovascular events.

Bacterial infections and impaired circulating mitochondrial DNA dynamics are associated with adverse pregnancy outcomes. Unmethylated cytosine-guanine dinucleotide (CpG) motifs are common in bacterial and mitochondrial DNA and act as potent immunostimulators. We tested the hypothesis that exposure to CpG oligonucleotides (ODN) during pregnancy would disrupt blood pressure circadian rhythms and placental molecular clock network, mediating aberrant fetoplacental growth dynamics. Rats were repeatedly treated with CpG ODN in the 3rd trimester (gestational day, GD, 14, 16, 18) and euthanized on GD20 (near term) or treated with a single dose of CpG ODN on GD14 and euthanized 4 hours after treatment. Hemodynamic circadian rhythms were analyzed via Lomb-Scargle periodogram analysis on 24-h raw data collected continuously via radiotelemetry. A p-value ≥ 0.05 indicates the absence of a circadian rhythm. Following the first treatment with CpG ODN, maternal systolic and diastolic blood pressure circadian rhythms were lost ( p ≥ 0.05). Blood pressure circadian rhythm was restored by GD16 and remained unaffected after the second treatment with CpG ODN ( p < 0.0001). Diastolic blood pressure circadian rhythm was again lost after the last treatment on GD18 ( p ≥ 0.05). CpG ODN increased placental expression of Per2, Per3, and Tnfα ( p ≤ 0.05) and affected fetoplacental growth dynamics, such as reduced fetal and placental weights that were disproportionately associated with increases in the number of resorptions in ODN-treated dams compared to controls. In conclusion, gestational exposure to unmethylated CpG ODN dysregulates placental molecular clock network and fetoplacental growth dynamics and disrupts blood pressure circadian rhythms.