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Item Open Access Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude.(Clinical epigenetics, 2023-09) Kadalayil, Latha; Alam, Md Zahangir; White, Cory Haley; Ghantous, Akram; Walton, Esther; Gruzieva, Olena; Merid, Simon Kebede; Kumar, Ashish; Roy, Ritu P; Solomon, Olivia; Huen, Karen; Eskenazi, Brenda; Rzehak, Peter; Grote, Veit; Langhendries, Jean-Paul; Verduci, Elvira; Ferre, Natalia; Gruszfeld, Darek; Gao, Lu; Guan, Weihua; Zeng, Xuehuo; Schisterman, Enrique F; Dou, John F; Bakulski, Kelly M; Feinberg, Jason I; Soomro, Munawar Hussain; Pesce, Giancarlo; Baiz, Nour; Isaevska, Elena; Plusquin, Michelle; Vafeiadi, Marina; Roumeliotaki, Theano; Langie, Sabine AS; Standaert, Arnout; Allard, Catherine; Perron, Patrice; Bouchard, Luigi; van Meel, Evelien R; Felix, Janine F; Jaddoe, Vincent WV; Yousefi, Paul D; Ramlau-Hansen, Cecilia H; Relton, Caroline L; Tobi, Elmar W; Starling, Anne P; Yang, Ivana V; Llambrich, Maria; Santorelli, Gillian; Lepeule, Johanna; Salas, Lucas A; Bustamante, Mariona; Ewart, Susan L; Zhang, Hongmei; Karmaus, Wilfried; Röder, Stefan; Zenclussen, Ana Claudia; Jin, Jianping; Nystad, Wenche; Page, Christian M; Magnus, Maria; Jima, Dereje D; Hoyo, Cathrine; Maguire, Rachel L; Kvist, Tuomas; Czamara, Darina; Räikkönen, Katri; Gong, Tong; Ullemar, Vilhelmina; Rifas-Shiman, Sheryl L; Oken, Emily; Almqvist, Catarina; Karlsson, Robert; Lahti, Jari; Murphy, Susan K; Håberg, Siri E; London, Stephanie; Herberth, Gunda; Arshad, Hasan; Sunyer, Jordi; Grazuleviciene, Regina; Dabelea, Dana; Steegers-Theunissen, Régine PM; Nohr, Ellen A; Sørensen, Thorkild IA; Duijts, Liesbeth; Hivert, Marie-France; Nelen, Vera; Popovic, Maja; Kogevinas, Manolis; Nawrot, Tim S; Herceg, Zdenko; Annesi-Maesano, Isabella; Fallin, M Daniele; Yeung, Edwina; Breton, Carrie V; Koletzko, Berthold; Holland, Nina; Wiemels, Joseph L; Melén, Erik; Sharp, Gemma C; Silver, Matt J; Rezwan, Faisal I; Holloway, John WBackground
Seasonal variations in environmental exposures at birth or during gestation are associated with numerous adult traits and health outcomes later in life. Whether DNA methylation (DNAm) plays a role in the molecular mechanisms underlying the associations between birth season and lifelong phenotypes remains unclear.Methods
We carried out epigenome-wide meta-analyses within the Pregnancy And Childhood Epigenetic Consortium to identify associations of DNAm with birth season, both at differentially methylated probes (DMPs) and regions (DMRs). Associations were examined at two time points: at birth (21 cohorts, N = 9358) and in children aged 1-11 years (12 cohorts, N = 3610). We conducted meta-analyses to assess the impact of latitude on birth season-specific associations at both time points.Results
We identified associations between birth season and DNAm (False Discovery Rate-adjusted p values < 0.05) at two CpGs at birth (winter-born) and four in the childhood (summer-born) analyses when compared to children born in autumn. Furthermore, we identified twenty-six differentially methylated regions (DMR) at birth (winter-born: 8, spring-born: 15, summer-born: 3) and thirty-two in childhood (winter-born: 12, spring and summer: 10 each) meta-analyses with few overlapping DMRs between the birth seasons or the two time points. The DMRs were associated with genes of known functions in tumorigenesis, psychiatric/neurological disorders, inflammation, or immunity, amongst others. Latitude-stratified meta-analyses [higher (≥ 50°N), lower (< 50°N, northern hemisphere only)] revealed differences in associations between birth season and DNAm by birth latitude. DMR analysis implicated genes with previously reported links to schizophrenia (LAX1), skin disorders (PSORS1C, LTB4R), and airway inflammation including asthma (LTB4R), present only at birth in the higher latitudes (≥ 50°N).Conclusions
In this large epigenome-wide meta-analysis study, we provide evidence for (i) associations between DNAm and season of birth that are unique for the seasons of the year (temporal effect) and (ii) latitude-dependent variations in the seasonal associations (spatial effect). DNAm could play a role in the molecular mechanisms underlying the effect of birth season on adult health outcomes.Item Open Access Body Mass and Tail Girth Predict Hibernation Expression in Captive Dwarf Lemurs.(Physiological and biochemical zoology : PBZ, 2022-03) Blanco, Marina B; Greene, Lydia K; Klopfer, Peter H; Lynch, Danielle; Browning, Jenna; Ehmke, Erin E; Yoder, Anne DAbstractHibernation, a metabolic strategy, allows individuals to reduce energetic demands in times of energetic deficits. Hibernation is pervasive in nature, occurring in all major mammalian lineages and geographical regions; however, its expression is variable across species, populations, and individuals, suggesting that trade-offs are at play. Whereas hibernation reduces energy expenditure, energetically expensive arousals may impose physiological burdens. The torpor optimization hypothesis posits that hibernation should be expressed according to energy availability. The greater the energy surplus, the lower the hibernation output. The thrifty female hypothesis, a variation of the torpor optimization hypothesis, states that females should conserve more energy because of their more substantial reproductive costs. Contrarily, if hibernation's benefits offset its costs, hibernation may be maximized rather than optimized (e.g., hibernators with greater fat reserves could afford to hibernate longer). We assessed torpor expression in captive dwarf lemurs, primates that are obligate, seasonal, and tropical hibernators. Across 4.5 mo in winter, we subjected eight individuals at the Duke Lemur Center to conditions conducive to hibernation, recorded estimates of skin temperature hourly (a proxy for torpor), and determined body mass and tail fat reserves bimonthly. Across and between consecutive weigh-ins, heavier dwarf lemurs spent less time in torpor and lost more body mass. At equivalent body mass, females spent more time torpid and better conserved energy than did males. Although preliminary, our results support the torpor optimization and thrifty female hypotheses, suggesting that individuals optimize rather than maximize torpor according to body mass. These patterns are consistent with hibernation phenology in Madagascar, where dwarf lemurs hibernate longer in more seasonal habitats.Item Open Access Body temperature and thermal environment in a generalized arboreal anthropoid, wild mantled howling monkeys (Alouatta palliata).(Am J Phys Anthropol, 2014-05) Thompson, Cynthia L; Williams, Susan H; Glander, Kenneth E; Teaford, Mark F; Vinyard, Christopher JFree-ranging primates are confronted with the challenge of maintaining an optimal range of body temperatures within a thermally dynamic environment that changes daily, seasonally, and annually. While many laboratory studies have been conducted on primate thermoregulation, we know comparatively little about the thermal pressures primates face in their natural, evolutionarily relevant environment. Such knowledge is critical to understanding the evolution of thermal adaptations in primates and for comparative evaluation of humans' unique thermal adaptations. We examined temperature and thermal environment in free-ranging, mantled howling monkeys (Alouatta palliata) in a tropical dry forest in Guanacaste, Costa Rica. We recorded subcutaneous (Tsc ) and near-animal ambient temperatures (Ta ) from 11 animals over 1586.5 sample hours during wet and dry seasons. Howlers displayed considerable variation in Tsc , which was largely attributable to circadian effects. Despite significant seasonal changes in the ambient thermal environment, howlers showed relatively little evidence for seasonal changes in Tsc . Howlers experienced warm thermal conditions which led to body cooling relative to the environment, and plateaus in Tsc at increasingly warm Ta . They also frequently faced cool thermal conditions (Ta < Tsc ) in which Tsc was markedly elevated compared with Ta . These data add to a growing body of evidence that non-human primates have more labile body temperatures than humans. Our data additionally support a hypothesis that, despite inhabiting a dry tropical environment, howling monkeys experience both warm and cool thermal pressures. This suggests that thermal challenges may be more prevalent for primates than previously thought, even for species living in nonextreme thermal environments.Item Open Access Comparing habitat suitability and connectivity modeling methods for conserving pronghorn migrations.(PloS one, 2012-01) Poor, Erin E; Loucks, Colby; Jakes, Andrew; Urban, Dean LTerrestrial long-distance migrations are declining globally: in North America, nearly 75% have been lost. Yet there has been limited research comparing habitat suitability and connectivity models to identify migration corridors across increasingly fragmented landscapes. Here we use pronghorn (Antilocapra americana) migrations in prairie habitat to compare two types of models that identify habitat suitability: maximum entropy (Maxent) and expert-based (Analytic Hierarchy Process). We used distance to wells, distance to water, NDVI, land cover, distance to roads, terrain shape and fence presence to parameterize the models. We then used the output of these models as cost surfaces to compare two common connectivity models, least-cost modeling (LCM) and circuit theory. Using pronghorn movement data from spring and fall migrations, we identified potential migration corridors by combining each habitat suitability model with each connectivity model. The best performing model combination was Maxent with LCM corridors across both seasons. Maxent out-performed expert-based habitat suitability models for both spring and fall migrations. However, expert-based corridors can perform relatively well and are a cost-effective alternative if species location data are unavailable. Corridors created using LCM out-performed circuit theory, as measured by the number of pronghorn GPS locations present within the corridors. We suggest the use of a tiered approach using different corridor widths for prioritizing conservation and mitigation actions, such as fence removal or conservation easements.Item Open Access Drinking from arboreal water sources by mantled howling monkeys (Alouatta palliata Gray).(Folia Primatol (Basel), 1978) Glander, KEDespite occasional trips to the ground and feeding in trees whose canopies touched the river, mantled howling monkeys were never seen to drink from any ground water. Drinking from arboreal cisterns was observed, but only during the wet season (meteorologically the less stressful season but phenologically the more stressful season). The lack of sufficient new leaves during the wet season forced the howlers to ingest more mature leaves which contained significantly less water. To compensate for the lowered amount of water in their food, the monkeys utilized arboreal water cisterns. The cisterns dried up during the dry season, but the howlers maintained their water balance by altering their time of actiivity and selecting a diet comprised largely of succulent new leaves. The effect of plant-produced secondary compounds on drinking also was discussed.Item Open Access Epidemiology, seasonality, and predictors of outcome of AIDS-associated Penicillium marneffei infection in Ho Chi Minh City, Viet Nam.(Clin Infect Dis, 2011-04-01) Le, Thuy; Wolbers, Marcel; Chi, Nguyen Huu; Quang, Vo Minh; Chinh, Nguyen Tran; Lan, Nguyen Phu Huong; Lam, Pham Si; Kozal, Michael J; Shikuma, Cecilia M; Day, Jeremy N; Farrar, JeremyBACKGROUND: Penicillium marneffei is an important human immunodeficiency virus (HIV)-associated opportunistic pathogen in Southeast Asia. The epidemiology and the predictors of penicilliosis outcome are poorly understood. METHODS: We performed a retrospective study of culture-confirmed incident penicilliosis admissions during 1996-2009 at the Hospital for Tropical Diseases in Ho Chi Minh City, Viet Nam. Seasonality of penicilliosis was assessed using cosinor models. Logistic regression was used to assess predictors of death or worsening disease based on 10 predefined covariates, and Cox regression was performed to model time-to-antifungal initiation. RESULTS: A total of 795 patients were identified; hospital charts were obtainable for 513 patients (65%). Cases increased exponentially and peaked in 2007 (156 cases), mirroring the trends in AIDS admissions during the study period. A highly significant seasonality for penicilliosis (P<.001) but not for cryptococcosis (P=.63) or AIDS admissions (P=.83) was observed, with a 27% (95% confidence interval, 14%-41%) increase in incidence during rainy months. All patients were HIV infected; the median CD4 cell count (62 patients) was 7 cells/μL (interquartile range, 4-24 cells/μL). Hospital outcome was an improvement in 347 (68%), death in 101 (20%), worsening in 42 (8%), and nonassessable in 23 (5%) cases. Injection drug use, shorter history, absence of fever or skin lesions, elevated respiratory rates, higher lymphocyte count, and lower platelet count independently predicted poor outcome in both complete-case and multiple-imputation analyses. Time-to-treatment initiation was shorter for patients with skin lesions (hazard ratio, 3.78; 95% confidence interval, 2.96-4.84; P<.001). CONCLUSIONS: Penicilliosis incidence correlates with the HIV/AIDS epidemic in Viet nam. The number of cases increases during rainy months. Injection drug use, shorter history, absence of fever or skin lesions, respiratory difficulty, higher lymphocyte count, and lower platelet count predict poor in-hospital outcome.Item Open Access Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange.(New Phytol, 2010-07) Domec, Jean-Christophe; King, John S; Noormets, Asko; Treasure, Emrys; Gavazzi, Michael J; Sun, Ge; McNulty, Steven G*Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. *By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of normal and below-normal precipitation, and examined its effects on tree transpiration, ecosystem water use and carbon exchange. *The occurrence of HR was explained by courses of reverse flow through roots. As the drought progressed, HR maintained soil moisture above 0.15 cm(3) cm(-3) and increased transpiration by 30-50%. HR accounted for 15-25% of measured total site water depletion seasonally, peaking at 1.05 mm d(-1). The understory species depended on water redistributed by the deep-rooted overstory pine trees for their early summer water supply. Modeling carbon flux showed that in the absence of HR, gross ecosystem productivity and net ecosystem exchange could be reduced by 750 and 400 g C m(-2) yr(-1), respectively. *Hydraulic redistribution mitigated the effects of soil drying on understory and stand evapotranspiration and had important implications for net primary productivity by maintaining this whole ecosystem as a carbon sink.Item Open Access Mechanical defenses in leaves eaten by Costa Rican howling monkeys (Alouatta palliata).(Am J Phys Anthropol, 2006-01) Glander, Kenneth Earl; Lucas, PW; Teaford, Mark F; Ungar, PSPrimate species often eat foods of different physical properties. This may have implications for tooth structure and wear in those species. The purpose of this study was to examine the mechanical defenses of leaves eaten by Alouatta palliata from different social groups at Hacienda La Pacifica in Costa Rica. Leaves were sampled from the home-ranges of groups living in different microhabitats. Specimens were collected during the wet and dry seasons from the same tree, same plant part, and same degree of development as those eaten by the monkeys. The toughness of over 300 leaves was estimated using a scissors test on a Darvell mechanical tester. Toughness values were compared between social groups, seasons, and locations on the leaves using ANOVA. Representative samples of leaves were also sun-dried for subsequent scanning electron microscopy and energy dispersive x-ray (EDX) analyses in an attempt to locate silica on the leaves. Both forms of mechanical defense (toughness and silica) were found to be at work in the plants at La Pacifica. Fracture toughness varied significantly by location within single leaves, indicating that measures of fracture toughness must be standardized by location on food items. Monkeys made some food choices based on fracture toughness by avoiding the toughest parts of leaves and consuming the least tough portions. Intergroup and seasonal differences in the toughness of foods suggest that subtle differences in resource availability can have a significant impact on diet and feeding in Alouatta palliata. Intergroup differences in the incidence of silica on leaves raise the possibility of matching differences in the rates and patterns of tooth wear.Item Open Access Mechanical defenses in leaves eaten by Costa Rican howling monkeys (Alouatta palliata).(Am J Phys Anthropol, 2006-01) Teaford, MF; Lucas, PW; Ungar, PS; Glander, KEPrimate species often eat foods of different physical properties. This may have implications for tooth structure and wear in those species. The purpose of this study was to examine the mechanical defenses of leaves eaten by Alouatta palliata from different social groups at Hacienda La Pacifica in Costa Rica. Leaves were sampled from the home-ranges of groups living in different microhabitats. Specimens were collected during the wet and dry seasons from the same tree, same plant part, and same degree of development as those eaten by the monkeys. The toughness of over 300 leaves was estimated using a scissors test on a Darvell mechanical tester. Toughness values were compared between social groups, seasons, and locations on the leaves using ANOVA. Representative samples of leaves were also sun-dried for subsequent scanning electron microscopy and energy dispersive x-ray (EDX) analyses in an attempt to locate silica on the leaves. Both forms of mechanical defense (toughness and silica) were found to be at work in the plants at La Pacifica. Fracture toughness varied significantly by location within single leaves, indicating that measures of fracture toughness must be standardized by location on food items. Monkeys made some food choices based on fracture toughness by avoiding the toughest parts of leaves and consuming the least tough portions. Intergroup and seasonal differences in the toughness of foods suggest that subtle differences in resource availability can have a significant impact on diet and feeding in Alouatta palliata. Intergroup differences in the incidence of silica on leaves raise the possibility of matching differences in the rates and patterns of tooth wear.Item Open Access Modifying the ‘pulse-reserve’ paradigm for deserts of North America: precipitation pulses, soil water and plant responses(Oecologia, 2004) REYNOLDS; James, F; Kemp, PR; Ogle, K; Fernández, RJThe 'pulse-reserve' conceptual model--arguably one of the most-cited paradigms in aridland ecology--depicts a simple, direct relationship between rainfall, which triggers pulses of plant growth, and reserves of carbon and energy. While the heuristics of 'pulses', 'triggers' and 'reserves' are intuitive and thus appealing, the value of the paradigm is limited, both as a conceptual model of how pulsed water inputs are translated into primary production and as a framework for developing quantitative models. To overcome these limitations, we propose a revision of the pulse-reserve model that emphasizes the following: (1) what explicitly constitutes a biologically significant 'rainfall pulse', (2) how do rainfall pulses translate into usable 'soil moisture pulses', and (3) how are soil moisture pulses differentially utilized by various plant functional types (FTs) in terms of growth? We explore these questions using the patch arid lands simulation (PALS) model for sites in the Mojave, Sonoran, and Chihuahuan deserts of North America. Our analyses indicate that rainfall variability is best understood in terms of sequences of rainfall events that produce biologically-significant 'pulses' of soil moisture recharge, as opposed to individual rain events. In the desert regions investigated, biologically significant pulses of soil moisture occur in either winter (October-March) or summer (July-September), as determined by the period of activity of the plant FTs. Nevertheless, it is difficult to make generalizations regarding specific growth responses to moisture pulses, because of the strong effects of and interactions between precipitation, antecedent soil moisture, and plant FT responses, all of which vary among deserts and seasons. Our results further suggest that, in most soil types and in most seasons, there is little separation of soil water with depth. Thus, coexistence of plant FTs in a single patch as examined in this PALS study is likely to be fostered by factors that promote: (1) separation of water use over time (seasonal differences in growth), (2) relative differences in the utilization of water in the upper soil layers, or (3) separation in the responses of plant FTs as a function of preceding conditions, i.e., the physiological and morphological readiness of the plant for water-uptake and growth. Finally, the high seasonal and annual variability in soil water recharge and plant growth, which result from the complex interactions that occur as a result of rainfall variability, antecedent soil moisture conditions, nutrient availability, and plant FT composition and cover, call into question the use of simplified vegetation models in forecasting potential impacts of climate change in the arid zones in North America.Item Open Access Plant responses to precipitation in desert ecosystems: integrating functional types, pulses, thresholds, and delays(Oecologia, 2004) Ogle, K; REYNOLDS, JFThe 'two-layer' and 'pulse-reserve' hypotheses were developed 30 years ago and continue to serve as the standard for many experiments and modeling studies that examine relationships between primary productivity and rainfall variability in aridlands. The two-layer hypothesis considers two important plant functional types (FTs) and predicts that woody and herbaceous plants are able to co-exist in savannas because they utilize water from different soil layers (or depths). The pulse-reserve model addresses the response of individual plants to precipitation and predicts that there are 'biologically important' rain events that stimulate plant growth and reproduction. These pulses of precipitation may play a key role in long-term plant function and survival (as compared to seasonal or annual rainfall totals as per the two-layer model). In this paper, we re-evaluate these paradigms in terms of their generality, strengths, and limitations. We suggest that while seasonality and resource partitioning (key to the two-layer model) and biologically important precipitation events (key to the pulse-reserve model) are critical to understanding plant responses to precipitation in aridlands, both paradigms have significant limitations. Neither account for plasticity in rooting habits of woody plants, potential delayed responses of plants to rainfall, explicit precipitation thresholds, or vagaries in plant phenology. To address these limitations, we integrate the ideas of precipitation thresholds and plant delays, resource partitioning, and plant FT strategies into a simple 'threshold-delay' model. The model contains six basic parameters that capture the nonlinear nature of plant responses to pulse precipitation. We review the literature within the context of our threshold-delay model to: (i) develop testable hypotheses about how different plant FTs respond to pulses; (ii) identify weaknesses in the current state-of-knowledge; and (iii) suggest future research directions that will provide insight into how the timing, frequency, and magnitude of rainfall in deserts affect plants, plant communities, and ecosystems.Item Open Access Q Fever, Scrub Typhus, and Rickettsial Diseases in Children, Kenya, 2011-2012.(Emerg Infect Dis, 2016-05) Maina, Alice N; Farris, Christina M; Odhiambo, Antony; Jiang, Ju; Laktabai, Jeremiah; Armstrong, Janice; Holland, Thomas; Richards, Allen L; O'Meara, Wendy PTo increase knowledge of undifferentiated fevers in Kenya, we tested paired serum samples from febrile children in western Kenya for antibodies against pathogens increasingly recognized to cause febrile illness in Africa. Of patients assessed, 8.9%, 22.4%, 1.1%, and 3.6% had enhanced seroreactivity to Coxiella burnetii, spotted fever group rickettsiae, typhus group rickettsiae, and scrub typhus group orientiae, respectively.Item Open Access Relative growth of the limbs and trunk in sifakas: heterochronic, ecological, and functional considerations.(Am J Phys Anthropol, 1993-12) Ravosa, MJ; Meyers, DM; Glander, KELimb, trunk, and body weight measurements were obtained for growth series of Milne-Edwards's diademed sifaka, Propithecus diadema edwardsi, and the golden-crowned sifaka, Propithecus tattersalli. Similar measures were obtained also for primarily adults of two subspecies of the western sifaka: Propithecus verreauxi coquereli, Coquerel's sifaka, and Propithecus verreauxi verreauxi, Verreaux's sifaka. Ontogenetic series for the larger-bodied P. d. edwardsi and the smaller-bodied P. tattersalli were compared to evaluate whether species-level differences in body proportions result from the differential extension of common patterns of relative growth. In bivariate plots, both subspecies of P. verreauxi were included to examine whether these taxa also lie along a growth trajectory common to all sifakas. Analyses of the data indicate that postcranial proportions for sifakas are ontogenetically scaled, much as demonstrated previously with cranial dimensions for all three species (Ravosa, 1992). As such, P. d. edwardsi apparently develops larger overall size primarily by growing at a faster rate, but not for a longer duration of time, than P. tattersalli and P. verreauxi; this is similar to results based on cranial data. A consideration of Malagasy lemur ecology suggests that regional differences in forage quality and resource availability have strongly influenced the evolutionary development of body-size variation in sifakas. On one hand, the rainforest environment of P. d. edwardsi imposes greater selective pressures for larger body size than the dry-forest environment of P. tattersalli and P. v. coquereli, or the semi-arid climate of P. v. verreauxi. On the other hand, as progressively smaller-bodied adult sifakas are located in the east, west, and northwest, this apparently supports suggestions that adult body size is set by dry-season constraints on food quality and distribution (i.e., smaller taxa are located in more seasonal habitats such as the west and northeast). Moreover, the fact that body-size differentiation occurs primarily via differences in growth rate is also due apparently to differences in resource seasonality (and juvenile mortality risk in turn) between the eastern rainforest and the more temperate northeast and west. Most scaling coefficients for both arm and leg growth range from slight negative allometry to slight positive allometry. Given the low intermembral index for sifakas, which is also an adaptation for propulsive hindlimb-dominated jumping, this suggests that differences in adult limb proportions are largely set prenatally rather than being achieved via higher rates of postnatal hindlimb growth.(ABSTRACT TRUNCATED AT 400 WORDS)Item Open Access Resistance of African tropical forests to an extreme climate anomaly.(Proceedings of the National Academy of Sciences of the United States of America, 2021-05) Bennett, Amy C; Dargie, Greta C; Cuni-Sanchez, Aida; Tshibamba Mukendi, John; Hubau, Wannes; Mukinzi, Jacques M; Phillips, Oliver L; Malhi, Yadvinder; Sullivan, Martin JP; Cooper, Declan LM; Adu-Bredu, Stephen; Affum-Baffoe, Kofi; Amani, Christian A; Banin, Lindsay F; Beeckman, Hans; Begne, Serge K; Bocko, Yannick E; Boeckx, Pascal; Bogaert, Jan; Brncic, Terry; Chezeaux, Eric; Clark, Connie J; Daniels, Armandu K; de Haulleville, Thales; Djuikouo Kamdem, Marie-Noël; Doucet, Jean-Louis; Evouna Ondo, Fidèle; Ewango, Corneille EN; Feldpausch, Ted R; Foli, Ernest G; Gonmadje, Christelle; Hall, Jefferson S; Hardy, Olivier J; Harris, David J; Ifo, Suspense A; Jeffery, Kathryn J; Kearsley, Elizabeth; Leal, Miguel; Levesley, Aurora; Makana, Jean-Remy; Mbayu Lukasu, Faustin; Medjibe, Vincent P; Mihindu, Vianet; Moore, Sam; Nssi Begone, Natacha; Pickavance, Georgia C; Poulsen, John R; Reitsma, Jan; Sonké, Bonaventure; Sunderland, Terry CH; Taedoumg, Hermann; Talbot, Joey; Tuagben, Darlington S; Umunay, Peter M; Verbeeck, Hans; Vleminckx, Jason; White, Lee JT; Woell, Hannsjoerg; Woods, John T; Zemagho, Lise; Lewis, Simon LThe responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015-2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species. Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015-2016 El Niño event. These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha-1 y-1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.Item Open Access Restoring diversity after cattail expansion: disturbance, resilience, and seasonality in a tropical dry wetland.(Ecol Appl, 2011-04) Osland, Michael J; González, Eugenio; Richardson, Curtis JAs the human footprint expands, ecologists and resource managers are increasingly challenged to explain and manage abrupt ecosystem transformations (i.e., regime shifts). In this study, we investigated the role of a mechanical disturbance that has been used to restore and maintain local wetland diversity after a monotypic regime shift in northwestern Costa Rica [specifically, an abrupt landscape-scale cattail (Typha) expansion]. The study was conducted in Palo Verde Marsh (Palo Verde National Park; a RAMSAR Wetland of International Importance), a seasonally flooded freshwater wetland that has historically provided habitat for large populations of wading birds and waterfowl. A cattail (T. domingensis) expansion in the 1980s greatly altered the plant community and reduced avian habitat. Since then, Typha has been managed using a form of mechanical disturbance called fangueo (a Spanish word, pronounced "fahn-gay-yo" in English). We applied a Typha removal treatment at three levels (control, fangueo, and fangueo with fencing to exclude cattle grazing). Fangueo resulted in a large reduction in Typha dominance (i.e., decreased aboveground biomass, ramet density, and ramet height) and an increase in habitat heterogeneity. As in many ecosystems that have been defined by multiple and frequent disturbances, a large portion of the plant community regenerated after disturbance (via propagule banking) and fangueo resulted in a more diverse plant community that was strongly dictated by seasonal processes (i.e., distinct wet- and dry-season assemblages). Importantly, the mechanical disturbance had no apparent short-term impact on any of the soil properties we measured (including bulk density). Interestingly, low soil and foliar N:P values indicate that Palo Verde Marsh and other wetlands in the region may be nitrogen limited. Our results quantify how, in a cultural landscape where the historical disturbance regime has been altered and diversity has declined, a mechanical disturbance in combination with seasonal drought and flooding has been used to locally restrict a clonal monodominant plant expansion, create habitat heterogeneity, and maintain plant diversity.Item Open Access Seasonal variations in air pollution particle-induced inflammatory mediator release and oxidative stress.(Environmental health perspectives, 2005-08) Becker, Susanne; Dailey, Lisa A; Soukup, Joleen M; Grambow, Steven C; Devlin, Robert B; Huang, Yuh-Chin THealth effects associated with particulate matter (PM) show seasonal variations. We hypothesized that these heterogeneous effects may be attributed partly to the differences in the elemental composition of PM. Normal human bronchial epithelial (NHBE) cells and alveolar macrophages (AMs) were exposed to equal mass of coarse [PM with aerodynamic diameter of 2.5-10 microm (PM(2.5-10)], fine (PM(2.5)), and ultrafine (PM(<0.1)) ambient PM from Chapel Hill, North Carolina, during October 2001 (fall) and January (winter), April (spring), and July (summer) 2002. Production of interleukin (IL)-8, IL-6, and reactive oxygen species (ROS) was measured. Coarse PM was more potent in inducing cytokines, but not ROSs, than was fine or ultrafine PM. In AMs, the October coarse PM was the most potent stimulator for IL-6 release, whereas the July PM consistently stimulated the highest ROS production measured by dichlorofluorescein acetate and dihydrorhodamine 123 (DHR). In NHBE cells, the January and the October PM were consistently the strongest stimulators for IL-8 and ROS, respectively. The July PM increased only ROS measured by DHR. PM had minimal effects on chemiluminescence. Principal-component analysis on elemental constituents of PM of all size fractions identified two factors, Cr/Al/Si/Ti/Fe/Cu and Zn/As/V/Ni/Pb/Se, with only the first factor correlating with IL-6/IL-8 release. Among the elements in the first factor, Fe and Si correlated with IL-6 release, whereas Cr correlated with IL-8 release. These positive correlations were confirmed in additional experiments with PM from all 12 months. These results indicate that elemental constituents of PM may in part account for the seasonal variations in PM-induced adverse health effects related to lung inflammation.Item Open Access Selective expression of insulin-like growth factor II in the songbird brain.(J Neurosci, 1997-09-15) Holzenberger, M; Jarvis, ED; Chong, C; Grossman, M; Nottebohm, F; Scharff, CNeuronal replacement occurs in the forebrain of juvenile and adult songbirds. To address the molecular processes that govern this replacement, we cloned the zebra finch insulin-like growth factor II (IGF-II) cDNA, a factor known to regulate neuronal development and survival in other systems, and examined its expression pattern by in situ hybridization and immunocytochemistry in juvenile and adult songbird brains. The highest levels of IGF-II mRNA expression occurred in three nuclei of the song system: in the high vocal center (HVC), in the medial magnocellular nucleus of the neostriatum (mMAN), which projects to HVC, and to a lesser extent in the robust nucleus of the archistriatum (RA), which receives projections from HVC. IGF-II mRNA expression was developmentally regulated in zebra finches. In canary HVC, monthly changes in IGF-II mRNA expression covaried with previously reported monthly differences in neuron incorporation. Combining retrograde tracers with in situ hybridization and immunocytochemistry, we determined that the HVC neurons that project to area X synthesize the IGF-II mRNA, whereas the adjacent RA-projecting neurons accumulate the IGF-II peptide. Our findings raise the possibility that within HVC IGF-II acts as a paracrine signal between nonreplaceable area X-projecting neurons and replaceable RA-projecting neurons, a mode of action that is compatible with the involvement of IGF-II with the replacement of neurons. Additional roles for IGF-II expression in songbird brain are likely, because expression also occurs in some brain areas outside the song system, among them the cerebellar Purkinje cells in which neurogenesis is not known to occur.Item Open Access Temperature and Precipitation Associate With Ischemic Stroke Outcomes in the United States.(Journal of the American Heart Association, 2018-11) Chu, Stacy Y; Cox, Margueritte; Fonarow, Gregg C; Smith, Eric E; Schwamm, Lee; Bhatt, Deepak L; Matsouaka, Roland A; Xian, Ying; Sheth, Kevin NBackground There is disagreement in the literature about the relationship between strokes and seasonal conditions. We sought to (1) describe seasonal patterns of stroke in the United States, and (2) determine the relationship between weather variables and stroke outcomes. Methods and Results We performed a cross-sectional study using Get With The Guidelines-Stroke data from 896 hospitals across the continental United States. We examined effects of season, climate region, and climate variables on stroke outcomes. We identified 457 638 patients admitted from 2011 to 2015 with ischemic stroke. There was a higher frequency of admissions in winter (116 862 in winter versus 113 689 in spring, 113 569 in summer, and 113 518 in fall; P<0.0001). Winter was associated with higher odds of in-hospital mortality (odds ratio [OR] 1.08 relative to spring, confidence interval [ CI ] 1.04-1.13, P=0.0004) and lower odds of discharge home ( OR 0.92, CI 0.91-0.94, P<0.0001) or independent ambulation at discharge ( OR 0.96, CI 0.94-0.98, P=0.0006). These differences were attenuated after adjusting for climate region and case mix and became inconsistent after controlling for weather variables. Temperature and precipitation were independently associated with outcome after multivariable analysis, with increases in temperature and precipitation associated with lower odds of mortality ( OR 0.95, CI 0.93-0.97, P<0.0001 and OR 0.95, CI 0.90-1.00, P=0.035, respectively). Conclusions Admissions for ischemic stroke were more frequent in the winter. Warmer and wetter weather conditions were independently associated with better outcomes. Further studies should aim to identify sensitive populations and inform public health measures aimed at resource allocation, readiness, and adaptive strategies.Item Open Access Thyroid hormone fluctuations indicate a thermoregulatory function in both a tropical (Alouatta palliata) and seasonally cold-habitat (Macaca fuscata) primate.(Am J Primatol, 2017-11) Thompson, Cynthia L; Powell, Brianna L; Williams, Susan H; Hanya, Goro; Glander, Kenneth E; Vinyard, Christopher JThyroid hormones boost animals' basal metabolic rate and represent an important thermoregulatory pathway for mammals that face cold temperatures. Whereas the cold thermal pressures experienced by primates in seasonal habitats at high latitudes and elevations are often apparent, tropical habitats also display distinct wet and dry seasons with modest changes in thermal environment. We assessed seasonal and temperature-related changes in thyroid hormone levels for two primate species in disparate thermal environments, tropical mantled howlers (Alouatta palliata), and seasonally cold-habitat Japanese macaques (Macaca fuscata). We collected urine and feces from animals and used ELISA to quantify levels of the thyroid hormone triiodothyronine (fT3). For both species, fT3levels were significantly higher during the cooler season (wet/winter), consistent with a thermoregulatory role. Likewise, both species displayed greater temperature deficits (i.e., the degree to which animals warm their body temperature relative to ambient) during the cooler season, indicating greater thermoregulatory pressures during this time. Independently of season, Japanese macaques displayed increasing fT3levels with decreasing recently experienced maximum temperatures, but no relationship between fT3and recently experienced minimum temperatures. Howlers increased fT3levels as recently experienced minimum temperatures decreased, although demonstrated the opposite relationship with maximum temperatures. This may reflect natural thermal variation in howlers' habitat: wet seasons had cooler minimum and mean temperatures than the dry season, but similar maximum temperatures. Overall, our findings support the hypothesis that both tropical howlers and seasonally cold-habitat Japanese macaques utilize thyroid hormones as a mechanism to boost metabolism in response to thermoregulatory pressures. This implies that cool thermal pressures faced by tropical primates are sufficient to invoke an energetically costly and relatively longer-term thermoregulatory pathway. The well-established relationship between thyroid hormones and energetics suggests that the seasonal hormonal changes we observed could influence many commonly studied behaviors including food choice, range use, and activity patterns.