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Journal articles on the topic 'Seasonal physiology'

Author: Grafiati
Published: 19 June 2022

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1

Pösö, A. Reeta. "Seasonal changes in reindeer physiology." Rangifer 25, no. 1 (April 1, 2005): 31–38. http://dx.doi.org/10.7557/2.25.1.335.

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The seasonal changes in the photoperiod, temperature and availability of food need to be converted to hormonal signals in order to induce adaptations in the physiology of the reindeer. The most reliable of the seasonal changes in the environment is the photoperiod, which affects the reindeer physiology through pineal gland and its hormone, melatonin. Usually there are large diurnal changes in the concentration of melatonin, but in the reindeer the daily rhythm disappears during the arctic summer to return again in the autumn. Seasonal changes in melatonin secretion are involved in the regulation of reproduction, the growth of pelage, thermogenesis, body mass and immune function. Melatonin may exert its effects through gene activation, but the mechanisms are not completely understood. Other hormones that show seasonality are thyroid hormones, insulin and leptin. Thus the observed physiological changes are a result of actions of several hormones. Appetite, energy production and thermogenesis are all vital for survival. During winter, when energy balance is negative, the reindeer uses mainly body fat for energy production. The use of fat stores is economical as the rate of lipolysis is controlled and the use of fatty acids in tissues such as muscle decreases. Only in severe starvation the rate of lipolysis increases enough to give rise to accumulation of ketone bodies. The protein mass is maintained and only in starved individuals muscle protein is used for energy production. The winter feed of the reindeer, the lichens, is poor in nitrogen and the nitrogen balance during winter is strongly negative. Reindeer responds to limited availability of nitrogen by increasing the recycling of urea into rumen. In general the adaptation of reindeer physiology enables the reindeer to survive the winter and although several aspects are known many others require further studies.Abstract in Finnish / Tiivistelmä: Valaistus, lämpötila ja ravinnon saatavuus vaihtelevat vuodenajn mukaan. Jotta nämä muutokset voisivat saada aikaan adaptiivisia muutoksia porossa, ne täytyy muutta hormonisignaaleiksi. Luotettavin näistä edellä mainituista ympäristön vuodenaikaismuutoksista on valo, joka vaikuttaa poron elintoimintoihin käpylisäkkeen ja sen erittämän hormonin, melatoniinin, välityksellä. Melatoniinin plasmapitoisuuksissa on havaittavissa selkeä vuorokausirytmi, joka porolla häviää kesällä ja alkaa uudestaan syksyllä. Melatoniini-hormonin vuodenaikaisvaihtelut ovat mukana säätelemässä lisääntymistä, talvikarvan kasvua, lämmöntuottoa, elopainoa ja immuunitoimintoja. Melatoniini vaikuttaa geeniaktivaation kautta mekanismeilla, joita ei vielä tarkkaan tunneta. Muita hormoneja, joiden erityksessä on havaittu vuodenaikaisvaihtelua, ovat kilpirauhashormonit, insuliini ja leptiini. Havaitut muutokset ovat ilmeisesti usean hormonin yhteisvaikutuksen aiheuttamia. Ruokahalu sekä energian- että lämmöntuotto ovat keskeisiä hengissä säilymisen kannalta. Talvella poron energiatase on negatiivinen ja se käyttää lähinnä varastoimiaan rasvoja energian tuottoon. Rasvojen käyttö on ekonomista, sillä rasvojen hajoaminen, lipolyysi, on säädeltyä ja rasvahappojen käyttö lihaksissa vähenee talvella. Vasta vakavasti nälkiintyneissä poroissa lipolyysi aktivoituu siten, että myös ketoaineita alkaa kertyä vereen. Valkuaisaineiden määrä vähenee vähemmän kuin rasvojen ja ainoastaan nälkiintyneet porot käyttävät lihasten valkuaisaineita energiantuottoon. Poron talviravinnossa, jäkälässä, on vain vähän typpeä, joten talvisin typpitasapaino on voimakkaasti negatiivinen. Poro reagoi tähän vähäiseen typpimäärään lisäämällä urean kierrätystä pötsiin. Kokonaisuudessaan poron elintoimintojen sopeutuminen auttaa poroa selviytymään talven yli. Vaikka adaptaatiosta on joiltakin osin kertynyt runsaasti tietoa, on siinä myös paljon selvitettävää.
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2

Skoner, David P., Barry Asman, and Philip Fireman. "Effect of Chlorpheniramine on Airway Physiology and Symptoms during Natural Pollen Exposure." American Journal of Rhinology 8, no. 1 (January 1994): 43–48. http://dx.doi.org/10.2500/105065894781882684.

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Previous studies have documented the changes in airway physiology which accompany natural pollen exposure. This study was designed to determine the effect of chlorpheniramine (8 mg b.i.d.) on seasonal changes in airway physiology and symptoms. Pollen counts, eustachian tube (ET) function, nasal resistance, mucociliary transport, and nasal symptoms were assessed weekly before, during, and after ragweed pollen season in 15 chlorpheniramine-treated and 15 placebo-treated allergic rhinitis (AR) subjects in a double-blind protocol and in 10 untreated control (non-AR) subjects. In placebo-treated AR subjects, the degree of congestion, rhinorrhea, sneezing, ET dysfunction, and nasal obstruction closely tracked pollen counts. However, symptoms, ET obstruction, and nasal obstruction persisted well beyond the temporal peak in pollen counts. There were no changes in mucociliary transport or pulmonary function during pollen exposure. Compared to placebo, chlorpheniramine-treated subjects manifested significantly less (p < .05) seasonal sneezing and rhinorrhea, but similar degrees of nasal congestion, ET dysfunction, and nasal obstruction. Pollen-related changes in nasal physiology and symptoms were not detected in the non-AR subjects. These data document that chlorpheniramine significantly attenuated the seasonal increases in rhinorrhea and sneezing, but did not lessen the concommitant physiologic alterations or the increase in nasal congestion.
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3

Bechtold, David A., and Andrew S. I. Loudon. "Hypothalamic Thyroid Hormones: Mediators of Seasonal Physiology." Endocrinology 148, no. 8 (August 1, 2007): 3605–7. http://dx.doi.org/10.1210/en.2007-0596.

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4

Köhler, Meike, Nekane Marín-Moratalla, Xavier Jordana, and Ronny Aanes. "Seasonal bone growth and physiology in endotherms shed light on dinosaur physiology." Nature 487, no. 7407 (June 27, 2012): 358–61. http://dx.doi.org/10.1038/nature11264.

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5

Wehr, Thomas A. "Melatonin and Seasonal Rhythms." Journal of Biological Rhythms 12, no. 6 (December 1997): 518–27. http://dx.doi.org/10.1177/074873049701200605.

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6

Smagula, Stephen F., Caitlin M. DuPont, Megan A. Miller, Robert T. Krafty, Brant P. Hasler, Peter L. Franzen, and Kathryn A. Roecklein. "Rest-activity rhythms characteristics and seasonal changes in seasonal affective disorder." Chronobiology International 35, no. 11 (July 19, 2018): 1553–59. http://dx.doi.org/10.1080/07420528.2018.1496094.

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7

Migaud, Martine, Martine Batailler, Delphine Pillon, Isabelle Franceschini, and Benoît Malpaux. "Seasonal Changes in Cell Proliferation in the Adult Sheep Brain and Pars Tuberalis." Journal of Biological Rhythms 26, no. 6 (November 30, 2011): 486–96. http://dx.doi.org/10.1177/0748730411420062.

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To adapt to seasonal variations in the environment, most mammalian species exhibit seasonal cycles in their physiology and behavior. Seasonal plasticity in the structure and function of the central nervous system contributes to the adaptation of this physiology in seasonal mammals. As part of these plasticity mechanisms, seasonal variations in proliferation rate and neuron production have been extensively studied in songbirds. In this report, we investigated whether this type of brain plasticity also occurs in sheep, a seasonal species, by assessing variations in cell proliferation in the sheep diencephalon. We administered the cell birth marker 5′-bromodeoxyuridine (BrdU) to adult female sheep in July and December, during long and short photoperiod, respectively. The BrdU incorporation was analyzed and quantified in the hypothalamus, a key center for neuroendocrine regulations, as well as in other structures involved in relaying neuroendocrine and sensory information, including the median eminence, the pars tuberalis of the pituitary gland, and the thalamus. In December, 2-fold and 6-fold increases in the number of BrdU+ nuclei were observed in the hypothalamus and thalamus, respectively, when compared with July. This variation is independent of the influence of peripheral gonadal estradiol variations. An inverse seasonal regulation of cell proliferation was observed in the pars tuberalis. In contrast, no seasonal variation in cell proliferation was seen in the subventricular zone of the lateral ventricle. Many of the newborn cells in the adult ovine hypothalamus and thalamus differentiate into neurons and glial cells, as assessed by the expression of neuronal (DCX, NeuN) and glial (GFAP, S100B) fate markers. In summary, we show that the estimated cell proliferation rates in the sheep hypothalamus, thalamus, and pars tuberalis are different between seasons. These variations are independent of the seasonal fluctuations of peripheral estradiol levels, unlike the results described in the brain nuclei involved in song control of avian species.
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8

Asikainen, Juha, Anne-Mari Mustonen, Heikki Hyvärinen, and Petteri Nieminen. "Seasonal Physiology of the Wild Raccoon Dog (Nyctereutes procyonoides)." Zoological Science 21, no. 4 (April 2004): 385–91. http://dx.doi.org/10.2108/zsj.21.385.

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9

Rutledge, James M., J. J. Volenec, R. H. Hurley, and Z. J. Reicher. "Seasonal Changes in Morphology and Physiology of Roughstalk Bluegrass." Crop Science 52, no. 2 (March 2012): 858–68. http://dx.doi.org/10.2135/cropsci2011.04.0225.

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10

Rusak, Benjamin. "Seasonal Affective Disorder: An Introduction." Journal of Biological Rhythms 3, no. 2 (June 1988): 97–99. http://dx.doi.org/10.1177/074873048800300201.

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11

Rosenthal, Norman E., David A. Sack, Robert G. Skwerer, Frederick M. Jacobsen, and Thomas A. Wehr. "Phototherapy for Seasonal Affective Disorder." Journal of Biological Rhythms 3, no. 2 (June 1988): 101–20. http://dx.doi.org/10.1177/074873048800300202.

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12

Garcia, Nicholas W., Timothy J. Greives, Devin A. Zysling, Susannah S. French, Emily M. Chester, and Gregory E. Demas. "Exogenous insulin enhances humoural immune responses in short-day, but not long-day, Siberian hamsters ( Phodopus sungorus )." Proceedings of the Royal Society B: Biological Sciences 277, no. 1691 (March 17, 2010): 2211–18. http://dx.doi.org/10.1098/rspb.2009.2230.

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Many animals experience marked seasonal fluctuations in environmental conditions. In response, animals display adaptive alterations in physiology and behaviour, including seasonal changes in immune function. During winter, animals must reallocate finite energy stores from relatively costly, less exigent systems (e.g. reproduction and immunity) to systems critical for immediate survival (e.g. thermoregulation). Seasonal changes in immunity are probably mediated by neuroendocrine factors signalling current energetic state. One potential hormonal candidate is insulin, a metabolic hormone released in response to elevated blood glucose levels. The aim of the present study was to explore the potential role of insulin in signalling energy status to the immune system in a seasonally breeding animal, the Siberian hamster ( Phodopus sungorus ). Specifically, exogenous insulin was administered to male hamsters housed in either long ‘summer-like’ or short ‘winter-like’ days. Animals were then challenged with an innocuous antigen and immune responses were measured. Insulin treatment significantly enhanced humoural immune responses in short, but not long days. In addition, insulin treatment increased food intake and decreased blood glucose levels across photoperiodic treatments. Collectively, these data support the hypothesis that insulin acts as an endocrine signal integrating seasonal energetic changes and immune responses in seasonally breeding rodents.
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13

Magnusson, Andres, and Diane Boivin. "Seasonal Affective Disorder: An Overview." Chronobiology International 20, no. 2 (January 2003): 189–207. http://dx.doi.org/10.1081/cbi-120019310.

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14

Freeman, David A. "Multiple neuroendocrine pathways mediate seasonal immunity." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 294, no. 2 (February 2008): R382—R383. http://dx.doi.org/10.1152/ajpregu.00856.2007.

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15

Vornanen, Matti, and Vesa Paajanen. "Seasonal changes in glycogen content and Na+-K+-ATPase activity in the brain of crucian carp." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 291, no. 5 (November 2006): R1482—R1489. http://dx.doi.org/10.1152/ajpregu.00172.2006.

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Changes in the number of Na+-K+-ATPase α-subunits, Na+-K+-ATPase activity and glycogen content of the crucian carp ( Carassius carassius) brain were examined to elucidate relative roles of energy demand and supply in adaptation to seasonal anoxia. Fish were collected monthly around the year from the wild for immediate laboratory assays. Equilibrium dissociation constant and Hill coefficient of [3H]ouabain binding to brain homogenates were 12.87 ± 2.86 nM and −1.18 ± 0.07 in June and 11.93 ± 2.81 nM and −1.17 ± 0.06 in February ( P > 0.05), respectively, suggesting little changes in Na+-K+-ATPase α-subunit composition of the brain between summer and winter. The number of [3H]ouabain binding sites and Na-K-ATPase activity varied seasonally ( P < 0.001) but did not show clear connection to seasonal changes in oxygen content of the fish habitat. Six weeks’ exposure of fish to anoxia in the laboratory did not affect Na+-K+-ATPase activity ( P > 0.05) confirming the anoxia resistance of the carp brain Na pump. Although anoxia did not suppress the Na pump, direct Q10 effect on Na+-K+-ATPase at low temperatures resulted in 10 times lower catalytic activity in winter than in summer. Brain glycogen content showed clear seasonal cycling with the peak value of 203.7 ± 16.1 μM/g in February and a 15 times lower minimum (12.9 ± 1.2) in July. In winter glycogen stores are 15 times larger and ATP requirements of Na+-K+-ATPase at least 10 times less than in summer. Accordingly, brain glycogen stores are sufficient to fuel brain function for about 8 min in summer and 16 h in winter, meaning about 150-fold extension of brain anoxia tolerance by seasonal changes in energy supply-demand ratio.
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16

Arnold, W. "Review: Seasonal differences in the physiology of wild northern ruminants." Animal 14 (2020): s124—s132. http://dx.doi.org/10.1017/s1751731119003240.

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17

Coleman, Gary D. "Physiology and Regulation of Seasonal Nitrogen Cycling in Woody Plants." Journal of Crop Improvement 10, no. 1-2 (May 24, 2004): 237–59. http://dx.doi.org/10.1300/j411v10n01_10.

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18

West, Alexander C., and Shona H. Wood. "Seasonal physiology: making the future a thing of the past." Current Opinion in Physiology 5 (October 2018): 1–8. http://dx.doi.org/10.1016/j.cophys.2018.04.006.

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19

Teets, Nicholas M., and Megan E. Meuti. "Hello Darkness, My Old Friend: A Tutorial of Nanda-Hamner Protocols." Journal of Biological Rhythms 36, no. 3 (March 15, 2021): 221–25. http://dx.doi.org/10.1177/0748730421998469.

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Plants and animals use circadian and photoperiodic timekeeping mechanisms to respond to daily and seasonal changes in light:dark and appropriately coordinate their development. Although the mechanisms that may connect the circadian and photoperiodic clock are still unclear in many species, researchers have been using Nanda-Hamner protocols for decades to elucidate how seasonal time is measured and determine whether seasonal responses have a circadian basis in a given species. In this brief tutorial we describe how to design and interpret the results of Nanda-Hamner experiments, and provide suggestions on how to use both Nanda-Hamner protocols and modern molecular experiments to better understand the mechanisms of seasonal timekeeping.
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20

Marazziti, Donatella, Lionella Palego, Chiara Mazzanti, Stefano Silvestri, and Giovanni B. Cassano. "Human Platelet Sulfotransferase Shows Seasonal Rhythms." Chronobiology International 12, no. 2 (January 1995): 100–105. http://dx.doi.org/10.3109/07420529509064505.

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21

Benedito‐Silva, Ana Amélia, Maria Laura Nogueira Pires, and Helena Maria Calil. "Seasonal Variation of Suicide in Brazil." Chronobiology International 24, no. 4 (January 2007): 727–37. http://dx.doi.org/10.1080/07420520701535795.

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22

Prendergast, Brian J., Randall A. Renstrom, and Randy J. Nelson. "Genetic Analyses of a Seasonal Interval Timer." Journal of Biological Rhythms 19, no. 4 (August 2004): 298–311. http://dx.doi.org/10.1177/0748730404266626.

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23

Maywood, Elizabeth S., Samira Chahad-Ehlers, Martine L. Garabette, Claire Pritchard, Phillip Underhill, Andrew Greenfield, Francis J. P. Ebling, et al. "Differential Testicular Gene Expression in Seasonal Fertility." Journal of Biological Rhythms 24, no. 2 (April 2009): 114–25. http://dx.doi.org/10.1177/0748730409332029.

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24

Skwerer, Robert G., Frederick M. Jacobsen, Connie C. Duncan, Karen A. Kelly, David A. Sack, Lawrence Tamarkin, Paul A. Gaist, Siegfried Kasper, and Norman E. Rosenthal. "Neurobiology of Seasonal Affective Disorder and Phototherapy." Journal of Biological Rhythms 3, no. 2 (June 1988): 135–54. http://dx.doi.org/10.1177/074873048800300204.

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25

Zucker, Irving. "Seasonal Affective Disorders: Animal Models Non Fingo." Journal of Biological Rhythms 3, no. 2 (June 1988): 209–23. http://dx.doi.org/10.1177/074873048800300208.

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26

Cornelius, Jamie M., Creagh W. Breuner, and Thomas P. Hahn. "Coping with the extremes: stress physiology varies between winter and summer in breeding opportunists." Biology Letters 8, no. 2 (October 19, 2011): 312–15. http://dx.doi.org/10.1098/rsbl.2011.0865.

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Seasonal changes in stress steroid hormone secretions are thought to reflect investment in self-maintenance versus reproduction. The capricious conditions hypothesis (CCH) posits that reduced corticosterone (CORT) secretion during stress coincident with parental phases of breeding is necessary in harsh environments because a full response would otherwise trigger repeated nest abandonments. To test this hypothesis, we measured seasonal changes in stress physiology in free-living red crossbills ( Loxia curvirostra ), an opportunistically breeding songbird that regularly breeds in summer and winter. This species allows unique comparisons of breeding physiology under very different seasonal environmental conditions within locations. We found strong support for the CCH: red crossbills showed reduced CORT secretion only when in high reproductive condition in the winter, when compared with summer breeders and winter non-breeders. These data demonstrate that behavioural status and local environmental conditions interact to affect mechanisms underlying investment trade-offs, presumably in a way that maximizes lifetime reproductive success.
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27

Rubin, Bruce K., Chris I. Cheeseman, Sita Gourishankar, and Malcolm King. "Is there a seasonal variation in mucus transport and nutrient absorption in the leopard frog?" Canadian Journal of Physiology and Pharmacology 70, no. 4 (April 1, 1992): 442–46. http://dx.doi.org/10.1139/y92-056.

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We postulated that as a hibernating species, frogs might have variable demands for nutrients at different seasons of the year and that this must be reflected in seasonal variations of physiologic processes related to nutrient transport and absorption. We examined the rate of mucus transport on the ciliated palate and the movement of nutrients across the intestinal lumen of leopard frogs, Rana pipiens. Mucus transport on the frog palate was strongly influenced by season, with maximal transport occurring in late June (Julian day 178, p = 0.0001; r = 0.58). This increased transport rate was associated with a summertime increase in mucus recoil (lower tangent δ) and a decrease in mucus hydration (increase in percent solids composition). Intestinal transport of leucine, lysine, and galactose did not appear to exhibit seasonal variability. These data suggest that different mechanisms may operate in determining seasonal variability in physiologic responses.Key words: mucociliary clearance, mucus viscoelasticity, intestinal absorption, Anura, seasonal variation.
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28

Ramirez-Otarola, Natalia, Daniel E. Naya, and Pablo Sabat. "Seasonal changes in digestive enzymes in five bird species." Canadian Journal of Zoology 96, no. 7 (July 2018): 707–12. http://dx.doi.org/10.1139/cjz-2017-0350.

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Most animals must cope with seasonal fluctuations in environmental conditions, including variations in food availability and composition. Accordingly, it is expected that most species should exhibit reversible seasonal phenotypic adjustments in their physiology. Here, we assessed seasonal variation in the activity of three digestive enzymes (sucrase, maltase, and aminopeptidase-N) in one omniviorous bird species (Rufous-collared Sparrow (Zonotrichia capensis (P. L. Statius Müller, 1776))), three granivorous bird species (Black-chinned Siskin (Carduelis barbata (Molina, 1782)), Common Diuca Finch (Diuca diuca (Molina, 1782)), and Mourning Sierra Finch (Phrygilus fruticeti (Kittlitz, 1833))), and one insectivorous bird species (Plain-mantled Tit-Spinetail (Leptasthenura aegithaloides (Kittlitz, 1830))). Based on the adaptive modulation hypothesis, we predicted that the omnivorous species should exhibit the largest seasonal variation in the activity of its digestive enzymes in relation to granivorous and insectivorous species. We found that Z. capensis adjusts total activities of disaccharidases, total sucrase activity varied between seasons in C. barbata, and total activity of aminopeptidase-N only changed seasonally in L. aegithaloides. Moreover, this last species modified the tissue-specific activity of both disaccharidases as well as the wet mass of its intestine. Taken together, our results suggest that seasonal dietary changes occur in most of the species, regardless of the trophic categories in which they belong. Consequently, a better knowledge of the diet and its seasonal variation is necessary to better account for the results recorded in this study.
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29

Obermüller, BE, SA Morley, DKA Barnes, and LS Peck. "Seasonal physiology and ecology of Antarctic marine benthic predators and scavengers." Marine Ecology Progress Series 415 (September 29, 2010): 109–26. http://dx.doi.org/10.3354/meps08735.

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30

Königer, Martina, Gary C. Harris, and Elise Kibler. "Seasonal changes in the physiology of shade leaves of Acer saccharum." Journal of Plant Physiology 157, no. 6 (December 2000): 627–36. http://dx.doi.org/10.1016/s0176-1617(00)80005-x.

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31

Lnenicka, Gregory A., and Yangu Zhao. "Seasonal differences in the physiology and morphology of crayfish motor terminals." Journal of Neurobiology 22, no. 6 (September 1991): 561–69. http://dx.doi.org/10.1002/neu.480220602.

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32

Larisch, Christina, Marcus Dittrich, Henning Wildhagen, Silke Lautner, Jörg Fromm, Andrea Polle, Rainer Hedrich, Heinz Rennenberg, Tobias Müller, and Peter Ache. "Poplar Wood Rays Are Involved in Seasonal Remodeling of Tree Physiology." Plant Physiology 160, no. 3 (September 19, 2012): 1515–29. http://dx.doi.org/10.1104/pp.112.202291.

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33

Dawson, Alistare, Arthur R. Goldsmith, and Ashi Chandola-Saklani. "Symposium: Endocrinology and physiology of puberty and seasonal breeding in birds." Journal of Ornithology 135, no. 3 (July 1994): 387–92. http://dx.doi.org/10.1007/bf01639980.

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34

Albright, Donna L., Ann M. Voda, Michael H. Smolensky, Bartholomew P. Hsi, and Michael Decker. "Seasonal Characteristics of and Age at Menarche." Chronobiology International 7, no. 3 (January 1990): 251–58. http://dx.doi.org/10.3109/07420529009056983.

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35

Persson, Roger, Anne Helene Garde, Åse Marie Hansen, Kai Österberg, Britt Larsson, Palle Ørbæk, and Björn Karlson. "Seasonal Variation in Human Salivary Cortisol Concentration." Chronobiology International 25, no. 6 (January 2008): 923–37. http://dx.doi.org/10.1080/07420520802553648.

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36

Cai, Zhi-Quan, Stefan A. Schnitzer, and Frans Bongers. "Seasonal differences in leaf-level physiology give lianas a competitive advantage over trees in a tropical seasonal forest." Oecologia 161, no. 1 (May 6, 2009): 25–33. http://dx.doi.org/10.1007/s00442-009-1355-4.

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37

Smith, Steven M., and James L. Weller. "Seasonal control of seed germination." New Phytologist 225, no. 5 (November 2019): 1821–23. http://dx.doi.org/10.1111/nph.16254.

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38

Liu, Qiang, and Fengri Li. "Spatial and Seasonal Variations of Standardized Photosynthetic Parameters under Different Environmental Conditions for Young Planted Larix olgensis Henry Trees." Forests 9, no. 9 (August 29, 2018): 522. http://dx.doi.org/10.3390/f9090522.

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Understanding the spatial and seasonal variations in leaf physiology is critical for accurately modeling the carbon uptake, physiological processes and growth of entire canopies and stands. For a 17-year-old Larix olgensis Henry plantation, vertical whorl-by-whorl sampling and analyses of seasonally repeated measurements of major photosynthetic parameters were conducted, and the correlations between photosynthetic parameters and environmental conditions, leaf morphological traits and spatial position within the crown were analyzed. According to the correlations, the photosynthetic parameters were standardized based on the environmental conditions to avoid the influence of the changing environment on the patterns of spatial and seasonal variations of photosynthetic parameters. The results showed that the standardized light-saturated net photosynthetic rate (SPmax), standardized dark respiration (SRd) and standardized stomatal conductance under saturated light (Sgs-sat) were all negatively related to the relative depth into the crown (RDINC) throughout the growing season. However, their vertical patterns were different during the development of the phenological phase. In addition, different gradients of environmental conditions also influenced the values and the range of the vertical variation in photosynthesis. High temperature and low humidity usually resulted in smaller values and weaker vertical variations of SPmax and Sgs-sat, but larger values and more obvious vertical variations in SRd. SPmax and Sgs-sat usually exhibited a parabolic seasonal pattern in different vertical positions within the crown; however, SRd generally followed a concave pattern. These seasonal patterns were all weaker with increasing RDINC. Different environments also exhibited a significant influence on the seasonal patterns of photosynthesis. We suggested that standardization is necessary before analyzing spatial and seasonal variations. A single environmental condition could not represent the spatial and seasonal patterns under all gradients of the environment. Spatial and seasonal variations should be simultaneously analyzed because they are related to each other.
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39

Bartness, T. J., J. A. Elliott, and B. D. Goldman. "Control of torpor and body weight patterns by a seasonal timer in Siberian hamsters." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 257, no. 1 (July 1, 1989): R142—R149. http://dx.doi.org/10.1152/ajpregu.1989.257.1.r142.

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Two experiments were designed to assess whether the short-day-induced patterns of shallow daily torpor, body weight, and other seasonal responses (food intake and pelage pigmentation) exhibited by Siberian hamsters (Phodopus sungorus sungorus) are under the control of a "seasonal timekeeping mechanism" that is independent of reproductive status [testosterone, (T)]. We examined whether the patterning and expression of these seasonal responses were altered by decreases in serum T that accompany gonadal regression during the first 8 wk of short-day exposure (i.e., the "preparatory phase" of the torpor season) or by experimental increases in serum T after this phase. Short-day-housed, castrated hamsters bearing T implants had long-day levels of the hormone and did not exhibit torpor. Appropriate seasonal patterns and levels of torpor, body weight, pelage color stage, and food intake were exhibited after T implant removal although serum T was clamped to long-day levels during the preparatory phase. In animals that were gonad intact during the preparatory phase and were subsequently castrated and given T implants, torpor did not occur as long as the implants were in place. However, the patterns and levels of daily torpor, food intake, and body weight rapidly returned to appropriate seasonal values compared with the castrated, blank-implanted controls on T implant removal; these effects occurred whether the T implants were removed when torpor frequency was increasing, at its peak, or decreasing across the torpor season. T did not affect pelage color stage under any condition.(ABSTRACT TRUNCATED AT 250 WORDS)
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40

Vornanen, M. "Seasonal and temperature-induced changes in myosin heavy chain composition of crucian carp hearts." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 267, no. 6 (December 1, 1994): R1567—R1573. http://dx.doi.org/10.1152/ajpregu.1994.267.6.r1567.

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Myosin heavy chain isoforms of the ventricular myocardium from crucian carp (Carassius carassius L.) hearts were analyzed in different times of the year by gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis [K. A. Esser, M. O. Boluyt, and T. P. White, Am. J. Physiol. 255 (Heart Circ. Physiol. 24): H659-H663, 1988]. In winter only one myosin heavy chain type was present, but in summer about one-half of the winter myosin was replaced by more slowly moving summer myosin. The occurrence of summer myosin correlated with seasonal changes in water temperature of the pond, where the fish were caught. Furthermore, the heavy chain composition of the heart was altered by temperature acclimation in the laboratory: cold-acclimated (2 degrees C) fish had only winter myosin, but warm-acclimated (22 degrees C) fish had both summer and winter myosin in about equal amounts. Myosin adenosinetriphosphatase activity of the hearts containing both summer and winter myosin was higher than that of hearts containing only winter myosin. Functionally, changes in myosin heavy chain composition were associated with inverse thermal acclimation in the heart rate. Warm-acclimated fish had higher in vitro heart rate and shorter contraction duration than cold-acclimated animals. Present findings suggest that changes in myosin heavy chain composition together with concomitant changes in Ca2+ activation of contraction make possible large seasonal alterations in the activity of crucian carp hearts. These adjustments are needed to adapt the cardiovascular system to winter hibernation and summer activity, which are dictated by seasonally bound changes in environmental conditions.
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41

Hellgren, Eric C., Michael R. Vaughan, and Roy L. Kirkpatrick. "Seasonal patterns in physiology and nutrition of black bears in Great Dismal Swamp, Virginia – North Carolina." Canadian Journal of Zoology 67, no. 8 (August 1, 1989): 1837–50. http://dx.doi.org/10.1139/z89-262.

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Diet quality, condition indices, and blood chemistry characteristics were determined for a black bear (Ursus americanus) population in the Great Dismal Swamp on the Atlantic Coastal Plain. Blood samples from 122 captures of 99 bears were analyzed. Seasonal shifts in diet composition were similar to previously reported findings for black bear food habits in the southeastern United States. Three major levels of diet quality were observed in terms of crude fiber, fat, and protein. Spring diets were high in protein but moderate in crude fiber. Condition indices (body weight, length/weight ratios) peaked in spring and late fall and were low during summer. Several blood characteristics (e.g., total protein, albumin, hematocrit, hemoglobin, and red blood cells) showed a similar annual rhythm (P < 0.01) for both sexes. Serum creatinine concentrations also varied seasonally (P < 0.001), with a peak during denning and high levels in spring and late fall, perhaps resulting from transition from and to hibernation. Urea/creatinine ratio was not a good indicator of the hibernating state, as 39 of 120 (32.5%) trapped bears had urea/creatinine ratios ≤ 10. Creatinine and total protein were the best indicators of the hibernating state. Albumin, hematocrit, hemoglobin, and red blood cells were the best indicators of condition during active stages, as correlations of condition indices and blood variables indicated significant (P < 0.1) associations between body condition and albumin, hematocrit, hemoglobin, and red blood cells. Nine blood variables varied with age (P < 0.1). Multivariate analysis of variance and discriminant function analysis using blood variables failed to reject the hypothesis that bears cycle through four metabolic stages throughout the year. Our results showed that metabolic shifts were tied to concomitant seasonal changes in diet quality, diet composition, and body condition. Comparison of our work with other published data on bear biology suggests that seasonal changes in bear physiology may be due partly to an endogenous rhythm.
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42

Pierre, Kamau, Naomi Schlesinger, and Ioannis P. Androulakis. "The role of the hypothalamic-pituitary-adrenal axis in modulating seasonal changes in immunity." Physiological Genomics 48, no. 10 (October 1, 2016): 719–38. http://dx.doi.org/10.1152/physiolgenomics.00006.2016.

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Seasonal changes in environmental conditions are accompanied by significant adjustment of multiple biological processes. In temperate regions, the day fraction, or photoperiod, is a robust environmental cue that synchronizes seasonal variations in neuroendocrine and metabolic function. In this work, we propose a semimechanistic mathematical model that considers the influence of seasonal photoperiod changes as well as cellular and molecular adaptations to investigate the seasonality of immune function. Our model predicts that the circadian rhythms of cortisol, our proinflammatory mediator, and its receptor exhibit seasonal differences in amplitude and phase, oscillating at higher amplitudes in the winter season with peak times occurring later in the day. Furthermore, the reduced photoperiod of winter coupled with seasonal alterations in physiological activity induces a more exacerbated immune response to acute stress, simulated in our studies as the administration of an acute dose of endotoxin. Our findings are therefore in accordance with experimental data that reflect the predominance of a proinflammatory state during the winter months. These changes in circadian rhythm dynamics may play a significant role in the seasonality of disease incidence and regulate the diurnal and seasonal variation of disease symptom severity.
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Putilov, Arcady A., Boris B. Pinchasov, and Elena Y. Poljakova. "Antidepressant effects of mono- and combined non-drug treatments for seasonal and non-seasonal depression." Biological Rhythm Research 36, no. 5 (December 2005): 405–21. http://dx.doi.org/10.1080/09291010500218480.

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Ebling, Francis JP. "Seasonal rhythms of energy metabolism." Biochemist 42, no. 2 (March 31, 2020): 16–20. http://dx.doi.org/10.1042/bio04202004.

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Most environments on our planet are highly seasonal, reflecting the tilt in the Earth’s axis relative to the sun. As a consequence, the majority of life forms have evolved profound seasonal variations in their behaviour and physiology that allow them to anticipate these patterns in food supply and to optimize their reproductive strategy. Reproduction is an energetically costly process in mammals, for example, in supporting pregnancy and then lactation in females. There has been strong selective pressure to ensure births occur in the optimal seasonal for survival. Terrestrial mammals indigenous to temperate and polar regions tend to give birth in spring, when the climatic conditions and food availability are conducive to survival. Seasonal cycles of reproduction also occur in equatorial regions, where they may be linked to wet and dry seasons. Only the species that have been domesticated by man or intensively bred, such as the laboratory strains of mice and rats, fail to display this seasonality. Given the intimate link between energy availability and reproductive success, it is no surprise that body systems regulating energy intake, storage and expenditure are themselves highly seasonal.
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Cugini, Pietro, Alfredo Romit, Loredana Di Palma, and Mario Giacovazzo. "Common Migraine as a Weekly and Seasonal Headache." Chronobiology International 7, no. 5-6 (January 1990): 467–69. http://dx.doi.org/10.3109/07420529009059158.

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Kanikowska, Dominika, Marian Grzymislawski, and Krzysztof Wiktorowicz. "Seasonal Rhythms of “Acute Phase Proteins” in Humans." Chronobiology International 22, no. 3 (January 2005): 591–96. http://dx.doi.org/10.1081/cbi-200062419.

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47

Koch, H. J., M. Klinkhammer‐Schalke, F. Hofstädter, U. Bogdahn, and P. Hau. "Seasonal Patterns of Birth in Patients with Glioblastoma." Chronobiology International 23, no. 5 (January 2006): 1047–52. http://dx.doi.org/10.1080/07420520600921088.

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48

Wan-long, Zhu, Yang Sheng-chang, Zhang Lin, and Wang Zheng-kun. "Seasonal variations of body mass, thermogenesis and digestive tract morphology in Apodemus chevrieri in Hengduan mountain region." Animal Biology 62, no. 4 (2012): 463–78. http://dx.doi.org/10.1163/157075612x650140.

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Seasonal changes in an animal’s morphology, physiology, and behavior are considered to be an adaptive strategy for survival and reproductive success. We hypothesize that Apodemus chevrieri will change their thermogenesis seasonally and serum leptin will change with body mass or body fat mass. Seasonal variations in body mass (BM), basal metabolic rate (BMR), nonshivering thermogenesis (NST), digestive tract morphology, serum leptin and uncoupling protein 1 (UCP1) were measured in wild-trapped A. chevrieri in Hengduan mountain region. The results showed that the body weight of A. chevrieri was lowest in winter and highest in summer. Decreased BM in the winter was accompanied by increased energy intake and enhanced NST and UCP1 as well as by decreased body fat mass, adjusted digestive tract morphology and reduced levels of circulating leptin. Further, serum leptin were positively correlated with body weight and body fat mass, and negatively correlated with energy intake and UCP1 contents. These data suggest that wild A. chevrieri do not depend on a decrease in BM, but instead increase their thermogenic capacity to cope with cold stress. Leptin may be involved in the seasonal regulation in energy balance and thermogenesis in field A. chevrieri.
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Gibiøki, Kornel. "A Review of Seasonal Periodicity in Peptic Ulcer Disease." Chronobiology International 4, no. 1 (1987): 91–99. http://dx.doi.org/10.3109/07420528709078512.

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50

Lei, Tze-Huan, Masashi Fujiwara, Nicola Gerrett, Tatsuro Amano, Toby Mündel, Yoshimitsu Inoue, Dai Okushima, Takeshi Nishiyasu, and Narihiko Kondo. "The effect of seasonal acclimatization on whole body heat loss response during exercise in a hot humid environment with different air velocity." Journal of Applied Physiology 131, no. 2 (August 1, 2021): 520–31. http://dx.doi.org/10.1152/japplphysiol.00837.2020.

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Seasonal acclimatization to humid heat enhances eccrine sweat gland function and thus results in a higher local and whole body sweat rate but does not attenuate Tcore during exercise in a hot-humid environment. Sweating efficiency is lower after seasonal acclimatization to humid heat compared with preacclimatization with and without the increase of air velocity. However, having a lower sweating efficiency does not mitigate the Tcore response during exercise in a hot-humid environment.
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