Browsing by Subject "Acclimatization"

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    An assessment of skin temperature gradients in a tropical primate using infrared thermography and subcutaneous implants.
    (J Therm Biol, 2017-01) Thompson, Cynthia L; Scheidel, Caleb; Glander, Kenneth E; Williams, Susan H; Vinyard, Christopher J
    Infrared thermography has become a useful tool to assess surface temperatures of animals for thermoregulatory research. However, surface temperatures are an endpoint along the body's core-shell temperature gradient. Skin and fur are the peripheral tissues most exposed to ambient thermal conditions and are known to serve as thermosensors that initiate thermoregulatory responses. Yet relatively little is known about how surface temperatures of wild mammals measured by infrared thermography relate to subcutaneous temperatures. Moreover, this relationship may differ with the degree that fur covers the body. To assess the relationship between temperatures and temperature gradients in peripheral tissues between furred and bare areas, we collected data from wild mantled howling monkeys (Alouatta palliata) in Costa Rica. We used infrared thermography to measure surface temperatures of the furred dorsum and bare facial areas of the body, recorded concurrent subcutaneous temperatures in the dorsum, and measured ambient thermal conditions via a weather station. Temperature gradients through cutaneous tissues (subcutaneous-surface temperature) and surface temperature gradients (surface-ambient temperature) were calculated. Our results indicate that there are differences in temperatures and temperature gradients in furred versus bare areas of mantled howlers. Under natural thermal conditions experienced by wild animals, the bare facial areas were warmer than temperatures in the furred dorsum, and cutaneous temperature gradients in the face were more variable than the dorsum, consistent with these bare areas acting as thermal windows. Cutaneous temperature gradients in the dorsum were more closely linked to subcutaneous temperatures, while facial temperature gradients were more heavily influenced by ambient conditions. These findings indicate that despite the insulative properties of fur, for mantled howling monkeys surface temperatures of furred areas still demonstrate a relationship with subcutaneous temperatures. Given that most mammals possess dense fur, this provides insight for using infrared imaging in thermoregulatory studies of wild animals lacking bare skin.
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    Anti-hypotensive treatment and endothelin blockade synergistically antagonize exercise fatigue in rats under simulated high altitude.
    (PLoS One, 2014) Radiloff, Daniel; Zhao, Yulin; Boico, Alina; Blueschke, Gert; Palmer, Gregory; Fontanella, Andrew; Dewhirst, Mark; Piantadosi, Claude A; Noveck, Robert; Irwin, David; Hamilton, Karyn; Klitzman, Bruce; Schroeder, Thies
    Rapid ascent to high altitude causes illness and fatigue, and there is a demand for effective acute treatments to alleviate such effects. We hypothesized that increased oxygen delivery to the tissue using a combination of a hypertensive agent and an endothelin receptor A antagonist drugs would limit exercise-induced fatigue at simulated high altitude. Our data showed that the combination of 0.1 mg/kg ambrisentan with either 20 mg/kg ephedrine or 10 mg/kg methylphenidate significantly improved exercise duration in rats at simulated altitude of 4,267 m, whereas the individual compounds did not. In normoxic, anesthetized rats, ephedrine alone and in combination with ambrisentan increased heart rate, peripheral blood flow, carotid and pulmonary arterial pressures, breathing rate, and vastus lateralis muscle oxygenation, but under inspired hypoxia, only the combination treatment significantly enhanced muscle oxygenation. Our results suggest that sympathomimetic agents combined with endothelin-A receptor blockers offset altitude-induced fatigue in rats by synergistically increasing the delivery rate of oxygen to hypoxic muscle by concomitantly augmenting perfusion pressure and improving capillary conductance in the skeletal muscle. Our findings might therefore serve as a basis to develop an effective treatment to prevent high-altitude illness and fatigue in humans.
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    Long-term thermal sensitivity of Earth's tropical forests.
    (Science (New York, N.Y.), 2020-05-21) Sullivan, Martin JP; Lewis, Simon L; Affum-Baffoe, Kofi; Castilho, Carolina; Costa, Flávia; Sanchez, Aida Cuni; Ewango, Corneille EN; Hubau, Wannes; Marimon, Beatriz; Monteagudo-Mendoza, Abel; Qie, Lan; Sonké, Bonaventure; Martinez, Rodolfo Vasquez; Baker, Timothy R; Brienen, Roel JW; Feldpausch, Ted R; Galbraith, David; Gloor, Manuel; Malhi, Yadvinder; Aiba, Shin-Ichiro; Alexiades, Miguel N; Almeida, Everton C; de Oliveira, Edmar Almeida; Dávila, Esteban Álvarez; Loayza, Patricia Alvarez; Andrade, Ana; Vieira, Simone Aparecida; Aragão, Luiz EOC; Araujo-Murakami, Alejandro; Arets, Eric JMM; Arroyo, Luzmila; Ashton, Peter; Aymard C, Gerardo; Baccaro, Fabrício B; Banin, Lindsay F; Baraloto, Christopher; Camargo, Plínio Barbosa; Barlow, Jos; Barroso, Jorcely; Bastin, Jean-François; Batterman, Sarah A; Beeckman, Hans; Begne, Serge K; Bennett, Amy C; Berenguer, Erika; Berry, Nicholas; Blanc, Lilian; Boeckx, Pascal; Bogaert, Jan; Bonal, Damien; Bongers, Frans; Bradford, Matt; Brearley, Francis Q; Brncic, Terry; Brown, Foster; Burban, Benoit; Camargo, José Luís; Castro, Wendeson; Céron, Carlos; Ribeiro, Sabina Cerruto; Moscoso, Victor Chama; Chave, Jerôme; Chezeaux, Eric; Clark, Connie J; de Souza, Fernanda Coelho; Collins, Murray; Comiskey, James A; Valverde, Fernando Cornejo; Medina, Massiel Corrales; da Costa, Lola; Dančák, Martin; Dargie, Greta C; Davies, Stuart; Cardozo, Nallaret Davila; de Haulleville, Thales; de Medeiros, Marcelo Brilhante; Del Aguila Pasquel, Jhon; Derroire, Géraldine; Di Fiore, Anthony; Doucet, Jean-Louis; Dourdain, Aurélie; Droissart, Vincent; Duque, Luisa Fernanda; Ekoungoulou, Romeo; Elias, Fernando; Erwin, Terry; Esquivel-Muelbert, Adriane; Fauset, Sophie; Ferreira, Joice; Llampazo, Gerardo Flores; Foli, Ernest; Ford, Andrew; Gilpin, Martin; Hall, Jefferson S; Hamer, Keith C; Hamilton, Alan C; Harris, David J; Hart, Terese B; Hédl, Radim; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Hladik, Annette; Coronado, Eurídice Honorio; Huamantupa-Chuquimaco, Isau; Huasco, Walter Huaraca; Jeffery, Kathryn J; Jimenez-Rojas, Eliana; Kalamandeen, Michelle; Djuikouo, Marie Noël Kamdem; Kearsley, Elizabeth; Umetsu, Ricardo Keichi; Kho, Lip Khoon; Killeen, Timothy; Kitayama, Kanehiro; Klitgaard, Bente; Koch, Alexander; Labrière, Nicolas; Laurance, William; Laurance, Susan; Leal, Miguel E; Levesley, Aurora; Lima, Adriano JN; Lisingo, Janvier; Lopes, Aline P; Lopez-Gonzalez, Gabriela; Lovejoy, Tom; Lovett, Jon C; Lowe, Richard; Magnusson, William E; Malumbres-Olarte, Jagoba; Manzatto, Ângelo Gilberto; Marimon, Ben Hur; Marshall, Andrew R; Marthews, Toby; de Almeida Reis, Simone Matias; Maycock, Colin; Melgaço, Karina; Mendoza, Casimiro; Metali, Faizah; Mihindou, Vianet; Milliken, William; Mitchard, Edward TA; Morandi, Paulo S; Mossman, Hannah L; Nagy, Laszlo; Nascimento, Henrique; Neill, David; Nilus, Reuben; Vargas, Percy Núñez; Palacios, Walter; Camacho, Nadir Pallqui; Peacock, Julie; Pendry, Colin; Peñuela Mora, Maria Cristina; Pickavance, Georgia C; Pipoly, John; Pitman, Nigel; Playfair, Maureen; Poorter, Lourens; Poulsen, John R; Poulsen, Axel Dalberg; Preziosi, Richard; Prieto, Adriana; Primack, Richard B; Ramírez-Angulo, Hirma; Reitsma, Jan; Réjou-Méchain, Maxime; Correa, Zorayda Restrepo; de Sousa, Thaiane Rodrigues; Bayona, Lily Rodriguez; Roopsind, Anand; Rudas, Agustín; Rutishauser, Ervan; Abu Salim, Kamariah; Salomão, Rafael P; Schietti, Juliana; Sheil, Douglas; Silva, Richarlly C; Espejo, Javier Silva; Valeria, Camila Silva; Silveira, Marcos; Simo-Droissart, Murielle; Simon, Marcelo Fragomeni; Singh, James; Soto Shareva, Yahn Carlos; Stahl, Clement; Stropp, Juliana; Sukri, Rahayu; Sunderland, Terry; Svátek, Martin; Swaine, Michael D; Swamy, Varun; Taedoumg, Hermann; Talbot, Joey; Taplin, James; Taylor, David; Ter Steege, Hans; Terborgh, John; Thomas, Raquel; Thomas, Sean C; Torres-Lezama, Armando; Umunay, Peter; Gamarra, Luis Valenzuela; van der Heijden, Geertje; van der Hout, Peter; van der Meer, Peter; van Nieuwstadt, Mark; Verbeeck, Hans; Vernimmen, Ronald; Vicentini, Alberto; Vieira, Ima Célia Guimarães; Torre, Emilio Vilanova; Vleminckx, Jason; Vos, Vincent; Wang, Ophelia; White, Lee JT; Willcock, Simon; Woods, John T; Wortel, Verginia; Young, Kenneth; Zagt, Roderick; Zemagho, Lise; Zuidema, Pieter A; Zwerts, Joeri A; Phillips, Oliver L
    The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (-9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth's climate.
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    Olfactory Receptor Subgenomes Linked with Broad Ecological Adaptations in Sauropsida.
    (Mol Biol Evol, 2015-11) Khan, Imran; Yang, Zhikai; Maldonado, Emanuel; Li, Cai; Zhang, Guojie; Gilbert, M Thomas P; Jarvis, Erich D; O'Brien, Stephen J; Johnson, Warren E; Antunes, Agostinho
    Olfactory receptors (ORs) govern a prime sensory function. Extant birds have distinct olfactory abilities, but the molecular mechanisms underlining diversification and specialization remain mostly unknown. We explored OR diversity in 48 phylogenetic and ecologically diverse birds and 2 reptiles (alligator and green sea turtle). OR subgenomes showed species- and lineage-specific variation related with ecological requirements. Overall 1,953 OR genes were identified in reptiles and 16,503 in birds. The two reptiles had larger OR gene repertoires (989 and 964 genes, respectively) than birds (182-688 genes). Overall, birds had more pseudogenes (7,855) than intact genes (1,944). The alligator had significantly more functional genes than sea turtle, likely because of distinct foraging habits. We found rapid species-specific expansion and positive selection in OR14 (detects hydrophobic compounds) in birds and in OR51 and OR52 (detect hydrophilic compounds) in sea turtle, suggestive of terrestrial and aquatic adaptations, respectively. Ecological partitioning among birds of prey, water birds, land birds, and vocal learners showed that diverse ecological factors determined olfactory ability and influenced corresponding olfactory-receptor subgenome. OR5/8/9 was expanded in predatory birds and alligator, suggesting adaptive specialization for carnivory. OR families 2/13, 51, and 52 were correlated with aquatic adaptations (water birds), OR families 6 and 10 were more pronounced in vocal-learning birds, whereas most specialized land birds had an expanded OR family 14. Olfactory bulb ratio (OBR) and OR gene repertoire were correlated. Birds that forage for prey (carnivores/piscivores) had relatively complex OBR and OR gene repertoires compared with modern birds, including passerines, perhaps due to highly developed cognitive capacities facilitating foraging innovations.