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6 results on '"cycle circadien"'

1. Diurnal? Calling activity patterns reveal nocturnal habits in the aposematic toad Melanophryniscus rubriventris.

Author

Pereyra, L.C., Akmentins, M.S., Sanabria, E.A., and Vaira, M.

Subjects
*BUFONIDAE, *CIRCADIAN rhythms in animals, *TOAD sounds, *ABIOTIC environment, *PHENOTYPIC plasticity, *AMPHIBIANS
Abstract

In diurnal species with short breeding seasons, an extension of diel activity to the night hours could be favoured to maximize mating opportunities, but individuals must deal with physiological and behavioural constraints. We tested this hypothesis in the Yungas Red-belly Toad ( Melanophryniscus rubriventris (Vellard, 1947)). We registered the diel pattern of male calling activity in two localities using automated recording systems, and related it to abiotic factors such as temperature, relative air humidity, and precipitation. The diel pattern of vocalization was mainly diurnal. Interestingly though, nocturnal calling activity was a common feature, representing between 40% and 43% of call records in both localities. Vocal activity was significantly influenced by time of the day and presence of rainfall. Calling males showed high plasticity, with activity in the entire environmental range of relative air humidity and temperature. Nocturnal calling seems to play an important role in the mating strategy of males, and it is probably more frequent in the genus Melanophryniscus than currently assumed. We discuss the implications of our findings in relation to different aspects of ecology of the species and suggest that bright colouration in M. rubriventris might result from a compromise between several nonconflicting functions (e.g., aposematism and thermoregulation). [ABSTRACT FROM AUTHOR]

Published
2016
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2. Diel patterns of baseline glucocorticoids and stress responsiveness in a teleost fish (bluegill, Lepomis macrochirus).

Author

Cousineau, A., Midwood, J.D., Stamplecoskie, K., King, G., Suski, C.D., and Cooke, S.J.

Subjects
*CIRCADIAN rhythms, *GLUCOCORTICOIDS, *BLUEGILL, *BLUEGILL behavior, *OSTEICHTHYES, *PHYSIOLOGICAL stress, *MAMMALS
Abstract

Little is known about whether glucocorticoids (GC) and GC responsiveness vary on a diel basis in the wild, especially for fish. Using bluegill ( Lepomis macrochirus Rafinesque, 1819) as a model freshwater teleost fish, we tested whether baseline concentration and stress responsiveness of GCs (i.e., plasma glucose and cortisol) varied over a 24 h period. Blood samples from lake-dwelling wild bluegill were obtained across six periods representing a complete circadian cycle to determine GC levels in newly captured fish (i.e., within 3 min of capture; baseline), the maximum value (maximum) 45 min following exposure to a standardized aerial exposure stressor, and determining responsiveness (by subtracting minimum from maximum). Our results revealed that baseline glucose concentration did not vary on a diel basis, whereas baseline cortisol concentration did. Maximum and stress-induced glucose responsiveness varied significantly among several time periods with lowest values recorded at midnight and higher values at mid-day. Maximum and stress-induced cortisol responsiveness were consistent across time periods. Collectively, these data suggest that baseline concentrations and stress-induced values of GCs in a freshwater temperate teleost fish tend to be consistent across diel periods such that there is apparently an absence of strong GC diel patterns. [ABSTRACT FROM AUTHOR]

Published
2014
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3. Calendar cells and circannual cycle

Author

Dardente, Hugues, ProdInra, Archive Ouverte, Physiologie de la reproduction et des comportements [Nouzilly] (PRC), Centre National de la Recherche Scientifique (CNRS)-Université de Tours-Institut Français du Cheval et de l'Equitation [Saumur]-Institut National de la Recherche Agronomique (INRA), Institut National de la Recherche Agronomique (INRA)-Institut Français du Cheval et de l'Equitation [Saumur]-Université de Tours-Centre National de la Recherche Scientifique (CNRS), European Cooperation in Science and Technology (COST). BEL., and Institut National de la Recherche Agronomique (INRA)-Institut Français du Cheval et de l'Equitation [Saumur]-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.OT]Life Sciences [q-bio]/Other [q-bio.OT], [SDV.OT] Life Sciences [q-bio]/Other [q-bio.OT], neuroendocrinology, cycle circadien, neuroendocrinologie
Abstract

Calendar cells and circannual cycle. COST action BM1105

Published
2016

5. Annual and daily changes in plasma gonadotropin and sex steroids in relation to teleost gonad cycles

Author

Zohar and Billard

Subjects
endocrine system, oncorhynchus mykiss, variation annuelle, cyprinus carpio, cycle circadien, fish, teleost, gonad cycles, sex steroids, hormone plasmatique, hormone sexuelle, carpe, reproduction, poisson, salmo gairdneri, cyprinidae, stéroïde sexuel, truite arc en ciel, cycle sexuel
Abstract

Long-term (annual and seasonal) variations in plasma concentration of reproductive hormones (maturational gonadotropin GTH and sex steroids) have been studied in relation to the gonad cycle in some teleosts. Plasma GTH concentrations are low and increase only gradually during the major part of gonad development (vitellogenesis, spermatogenesis) but increase sharply towards the end of gametogenesis–that is, around the time of oocyte maturation and ovulation and before the start of spermiation. In females, plasma concentrations of 17β-estradiol and estrone rise continuously during vitellogenesis. In salmonids, after a decrease in 17β-estradiol concentration starting at the end of the vitellogenesis, there is a small peak in testosterone concentration followed by a strong transient rise in 17α-hydroxy-20β-dihydroprogesterone, which induces oocyte maturation. The concentrations of testosterone and 11-ketotestosterone rise during spermatogenesis. Maximal concentrations of 11-ketotestosterone were recorded in rainbow trout Salmo gairdneri just prior to the start of spermiation. Plasma concentrations of both androgens in this species dropped during spermiation, whereas that of 17α-hydroxy-20β-dihydroprogesterone showed an important rise. Short-term (circadian and ultradian) variations in concentrations of reproductive hormones in teleosts have been less studied. Daily fluctuations in plasma GTH and in sex steroid concentrations, the pattern of which depends on the development stage of the gonads, have been demonstrated in a few fish species. Pulsed gonadotropin secretion occurs in some phases of gametogenesis in rainbow trout and common carp Cyprinus carpio.

Published
1984

6. Daily changes in blood serum levels of 17beta-estradiol and 11-ketotestosterone in the mature carp cyprinus caprio L

Author

Beniarz, K., Sokolovska, M., Fostier, Alexis, EPLER, P., and Academy of Agriculture

Subjects
Male, fish, Carps, Estradiol, cyprinus carpio, carp, [SDV]Life Sciences [q-bio], hormone animale, cycle circadien, Cyprinidae, oestradiol, hormone sexuelle, carpe, Circadian Rhythm, poisson, maturation sexuelle, stéroïde sexuel, Animals, Female, Testosterone
Abstract

International audience; Daily changes in blood serum levels of 17 beta-estradiol and 11-ketotestosterone in the mature carp Cyprinus carpio were investigated. Fish were kept under natural light conditions (LD = 16:8) water temperature about 19 degrees C. Females and males were divided into 2 groups respectively. Each group was sampled every 4 h during 24 h beginning at 08:00 (group 1) and 10:00 (group 2). The 17 beta-estradiol assay included a chromatographic step which increased the specificity of the measurement while in 11-ketotestosterone assay a specific antibody was used, having a low cross reactivity with testosterone (1.1%). Data obtained in this work were statistically analyzed using cosinor circle with error ellipses. The highest levels of estradiol (0.46-0.58 ng/ml) were observed between 09:00 and 11:00 and of 11-ketotestosterone (2.09-3.00 ng/ml) between 10:00 and 12:00. It was proved statistically that changes in the estradiol and 11-ketotestosterone levels during 24 h are of circadian rhythm type. The problem of hormonal changes during 24 h, connected with sexual maturation of fish, is discussed.

Published
1986

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