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Chancellor S, Grasse B, Sakmar T, Scheel D, Brown JS, Santymire RM. Exploring the Effect of Age on the Reproductive and Stress Physiology of Octopus bimaculoides Using Dermal Hormones. Animals (Basel) 2023; 13:3115. [PMID: 37835721 PMCID: PMC10571824 DOI: 10.3390/ani13193115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Our goal was to validate the use of dermal swabs to evaluate both reproductive and stress physiology in the California two-spot octopus, Octopus bimaculoides. Our objectives were to (1) use dermal swabs to evaluate glucocorticoids and reproductive hormones of O. bimaculoides; (2) determine the influence of life stage on hormone production (glucocorticoids in all individuals; testosterone, estrogen, and progesterone in females; and testosterone in males) of reproductive (n = 4) and senescent (n = 8) individuals to determine the effect of age on hormonal patterns; and (3) determine whether these hormones change significantly in response to an acute stressor. For the stress test, individuals were first swabbed for a baseline and then chased around the aquarium with a net for 5 min. Afterward, individuals were swabbed for 2 h at 15 min intervals to compare to the pre-stress test swab. Reproductive individuals responded to the stressor with a 2-fold increase in dermal cortisol concentrations at 15 and 90 min. Six of the eight senescent individuals did not produce a 2-fold increase in dermal cortisol concentrations. Reproductive individuals had significantly higher sex hormone concentrations compared to senescent individuals (progesterone and estradiol measured in females, and testosterone for both sexes). After the stressor, only reproductive males produced a 2-fold increase in dermal testosterone concentrations, while sex hormones in females showed no change. The stress hormone cortisol was significantly higher in senescent than in reproductive individuals, independent of sex. Dermal corticosterone concentrations were highest in senescent females followed by senescent males, and lowest in reproductive individuals regardless of sex. Dermal swabs provide an effective and noninvasive means for evaluating octopus hormones. Application of these indicators may be imperative as cephalopods are more commonly cultured in captivity for experimentation, display, and consumption.
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Affiliation(s)
| | - Bret Grasse
- Marine Biological Laboratory, Woods Hole, MA 02543, USA; (B.G.); (T.S.)
| | - Taylor Sakmar
- Marine Biological Laboratory, Woods Hole, MA 02543, USA; (B.G.); (T.S.)
| | - David Scheel
- Institute of Culture and the Environment, Alaska Pacific University, Anchorage, AK 99508, USA;
| | - Joel S. Brown
- Department of Integrated Mathematical Oncology, Moffitt Cancer Center, Tampa, FL 33612, USA;
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Deviche P, Sweazea K, Angelier F. Past and future: Urbanization and the avian endocrine system. Gen Comp Endocrinol 2023; 332:114159. [PMID: 36368439 DOI: 10.1016/j.ygcen.2022.114159] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/18/2022] [Accepted: 11/02/2022] [Indexed: 11/10/2022]
Abstract
Urban environments are evolutionarily novel and differ from natural environments in many respects including food and/or water availability, predation, noise, light, air quality, pathogens, biodiversity, and temperature. The success of organisms in urban environments requires physiological plasticity and adjustments that have been described extensively, including in birds residing in geographically and climatically diverse regions. These studies have revealed a few relatively consistent differences between urban and non-urban conspecifics. For example, seasonally breeding urban birds often develop their reproductive system earlier than non-urban birds, perhaps in response to more abundant trophic resources. In most instances, however, analyses of existing data indicate no general pattern distinguishing urban and non-urban birds. It is, for instance, often hypothesized that urban environments are stressful, yet the activity of the hypothalamus-pituitary-adrenal axis does not differ consistently between urban and non-urban birds. A similar conclusion is reached by comparing blood indices of metabolism. The origin of these disparities remains poorly understood, partly because many studies are correlative rather than aiming at establishing causality, which effectively limits our ability to formulate specific hypotheses regarding the impacts of urbanization on wildlife. We suggest that future research will benefit from prioritizing mechanistic approaches to identify environmental factors that shape the phenotypic responses of organisms to urbanization and the neuroendocrine and metabolic bases of these responses. Further, it will be critical to elucidate whether factors affect these responses (a) cumulatively or synergistically; and (b) differentially as a function of age, sex, reproductive status, season, and mobility within the urban environment. Research to date has used various taxa that differ greatly not only phylogenetically, but also with regard to ecological requirements, social systems, propensity to consume anthropogenic food, and behavioral responses to human presence. Researchers may instead benefit from standardizing approaches to examine a small number of representative models with wide geographic distribution and that occupy diverse urban ecosystems.
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Affiliation(s)
- Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ, USA.
| | - Karen Sweazea
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA
| | - Frederic Angelier
- Centre d'Etudes Biologiques de Chizé, UMR7372, CNRS - La Rochelle Universite, Villiers en Bois, France
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Wilsterman K, Alonge MM, Bao X, Conner KA, Bentley GE. Food access modifies GnIH, but not CRH, cell number in the hypothalamus in a female songbird. Gen Comp Endocrinol 2020; 292:113438. [PMID: 32060003 DOI: 10.1016/j.ygcen.2020.113438] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/06/2020] [Accepted: 02/10/2020] [Indexed: 11/23/2022]
Abstract
Food deprivation or restriction causes animals to mount a stereotypical behavioral and physiological response that involves overall increases in activity, elevated glucocorticoid production, and (often) inhibition of the reproductive system. Although there is increasing evidence that these responses can differ in their degree or covariation between the sexes, most studies to-date on food restriction/deprivation have focused on male songbirds. We therefore aimed to characterize the behavioral, physiological, and neuroendocrine response to acute food deprivation in a female songbird using a nomadic species, the zebra finch. We quantified behavior during a 6.5 h food deprivation and then measured physiological and neuroendocrine responses of female birds at the 6.5 h timepoint. Within 1 h of acute food deprivation, female zebra finches increased foraging behaviors, and after 6.5 h of food deprivation, females lost 5% of their body mass, on average. Change in body mass was positively associated with elevated corticosterone and (contrary to findings in male zebra finches) negatively related to the number of gonadotropin inhibitory hormone-immunoreactive cells in the hypothalamus. However, there was no effect of food deprivation on corticotropin releasing hormone-immunoreactive cells in the hypothalamus. There was also no relationship between corticotropin releasing hormone-immunoreactive cell number and circulating corticosterone. Our results are consistent with the hypothesis that neuroendocrine responses to food deprivation differ between male and female songbirds. Future studies should work to incorporate sex comparisons to evaluate sex-specific neuroendocrine responses to acute stress.
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Affiliation(s)
| | - Mattina M Alonge
- Integrative Biology, Univ. of California - Berkeley, Berkeley, CA, USA
| | - Xinmiao Bao
- Integrative Biology, Univ. of California - Berkeley, Berkeley, CA, USA
| | - Kristin A Conner
- Integrative Biology, Univ. of California - Berkeley, Berkeley, CA, USA
| | - George E Bentley
- Integrative Biology, Univ. of California - Berkeley, Berkeley, CA, USA; Helen Wills Neuroscience Institute, Univ. of California - Berkeley, Berkeley, CA, USA
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Deviche P, Bittner S, Gao S, Valle S. Roles and Mechanistic Bases of Glucocorticoid Regulation of Avian Reproduction. Integr Comp Biol 2018; 57:1184-1193. [PMID: 28985390 DOI: 10.1093/icb/icx112] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To maximize fitness, organisms must invest energetic and nutritional resources into developing, activating, and maintaining reproductive physiology and behavior. Corticosterone (CORT), the primary avian glucocorticoid, regulates energetic reserves to meet metabolic demands. At low (baseline) plasma levels, CORT activates avian mineralocorticoid receptors and may stimulate lipid mobilization, foraging activity, and feeding behavior. During stress in birds, elevated plasma CORT also stimulates glucocorticoid receptors and may promote glycemia, lipolysis, and proteolysis. Furthermore, CORT orchestrates physiological and behavioral adjustments to perceived threats. While many avian studies demonstrate effects of CORT on reproduction, few studies have elucidated the mechanisms, including receptor activation and site(s) of action, which underlie these effects. Even fewer studies have investigated how low and elevated plasma CORT regulates energetic reserves to meet the metabolic demands of reproduction. Here, we propose several hypotheses to clarify the direct and indirect effects of CORT on avian reproductive physiology and behavior. In addition, we emphasize the need for new manipulative studies involving alterations of endogenous plasma CORT levels and/or food availability to elucidate how CORT regulates the energetic demands of reproduction.
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Affiliation(s)
- Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Stephanie Bittner
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Sisi Gao
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Shelley Valle
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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Davies S, Beck ML, Sewall KB. Territorial aggression in urban and rural Song Sparrows is correlated with corticosterone, but not testosterone. Horm Behav 2018; 98:8-15. [PMID: 29166572 DOI: 10.1016/j.yhbeh.2017.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 11/06/2017] [Accepted: 11/17/2017] [Indexed: 02/09/2023]
Abstract
Urban songbirds of several species more vigorously defend their territories in response to conspecific song playback than do their rural counterparts, but the hormonal basis of this behavioral difference is unclear. It is well established in vertebrates that both testosterone and corticosterone affect the intensity of territoriality. Previous studies have found no evidence that initial (i.e., immediately following territorial challenge, but prior to restraint) plasma testosterone accounts for the elevated territorial aggression of urban birds. Determining if testosterone still contributes to urban-rural differences in territoriality requires also assessing males' abilities to transiently increase plasma testosterone (in response to an injection of gonadotropin-releasing hormone). We tested whether these hormones are correlated with the territorial response to conspecific song playback in urban and rural male Song Sparrows (Melospiza melodia) in Montgomery County, Virginia. We found that the elevated territorial aggression of urban sparrows was not related to variation in either initial plasma testosterone or the ability to transiently increase testosterone. In contrast, despite no overall habitat difference in initial corticosterone, levels of this hormone were positively correlated with territoriality in urban and rural sparrows. Furthermore, for a given level of corticosterone, urban sparrows were more territorially aggressive. Our findings suggest that initial corticosterone may either play a role in the regulation of persistent differences in territorial behavior between free-ranging urban and rural male Song Sparrows or be affected by the intensity of behavioral response to territorial challenge.
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Affiliation(s)
- Scott Davies
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Michelle L Beck
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Kendra B Sewall
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
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Ambardar M, Grindstaff JL. Pre-GnRH and GnRH-induced testosterone levels do not vary across behavioral contexts: A role for individual variation. Gen Comp Endocrinol 2017; 246:51-62. [PMID: 28322761 DOI: 10.1016/j.ygcen.2017.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/23/2017] [Accepted: 03/15/2017] [Indexed: 10/19/2022]
Abstract
Hormones can facilitate the expression of behavior, but relatively few studies have considered individual variation and repeatability in hormone-behavior relationships. Repeated measures of hormones are valuable because repeatability in hormone levels might be a mechanism that drives repeatability in behavior ("personality"). Testosterone is predicted to promote territorial aggression and suppress parental behaviors. In our population of eastern bluebirds (Sialia sialis), parental care and nest defense aggression toward a heterospecific are repeatable. We tested the hypothesis that repeatability of testosterone levels within individuals underlies repeatable behaviors observed in our population. We measured nestling provisioning and aggressive nest defense against a heterospecific. After behavioral observations we captured either the male or female bluebird, and determined initial testosterone levels and maximum capacity of the gonads to secrete testosterone by injecting gonadotropin-releasing hormone (GnRH). We found among-individual variation in initial testosterone levels for males and females. Individual males were repeatable in both initial and GnRH-induced testosterone levels across behavioral contexts, while individual females were repeatable in GnRH-induced testosterone levels. However, testosterone levels were not significantly related to parental or nest defense behaviors, suggesting that repeatable testosterone levels may not drive repeatable parental and heterospecific nest defense behaviors in this population. The absence of a relationship between testosterone and parental and heterospecific nest defense behaviors might be due to among-individual variation in testosterone levels. Considering the sources of variation in testosterone levels may reveal why some populations exhibit high individual variation in hormone levels.
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Affiliation(s)
- Medhavi Ambardar
- Department of Integrative Biology, 501 Life Science West, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Jennifer L Grindstaff
- Department of Integrative Biology, 501 Life Science West, Oklahoma State University, Stillwater, OK 74078, USA.
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Beck ML, Davies S, Moore IT, Schoenle LA, Kerman K, Vernasco BJ, Sewall KB. Beeswax corticosterone implants produce long-term elevation of plasma corticosterone and influence condition. Gen Comp Endocrinol 2016; 233:109-114. [PMID: 27222349 DOI: 10.1016/j.ygcen.2016.05.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/19/2016] [Accepted: 05/20/2016] [Indexed: 11/18/2022]
Abstract
Glucocorticoids can play a critical role in modulating life-history trade-offs. However, studying the effects of glucocorticoids on life-history often requires experimentally elevating plasma glucocorticoid concentrations for several weeks within normal physiological limits and without repeated handling of the animal. Recently, implants made of beeswax and testosterone (T) were shown to have release dynamics superior to some currently available T implants, and these beeswax implants dissolved, eliminating the need to recapture the animal. We evaluated the utility of beeswax implants containing four different dosages of corticosterone (CORT; the primary glucocorticoid in birds) and their effect on several condition indices in a captive colony of zebra finches (Taeniopygia guttata). The three implants with the greatest CORT doses (0.05, 0.1, and 0.5mg) produced spikes in plasma CORT concentrations 20h after treatment, but were within the limits that zebra finches may normally experience. The 0.5mg CORT implant elevated plasma CORT between typical baseline and restraint stress levels reported in other studies of zebra finches for the entire 35day experiment. Birds in the 0.5mg implant group were heavier, had greater furcular fat scores, and had lower hematocrit than birds in the control and other CORT implant groups. Beeswax CORT implants are a low cost method of elevating plasma CORT for a prolonged time. Furthermore, because there is no need to remove these implants at the end of a study, this method may be amenable to studies of free-ranging animals.
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Affiliation(s)
- Michelle L Beck
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA.
| | - Scott Davies
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA
| | - Ignacio T Moore
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA
| | - Laura A Schoenle
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA
| | - Kaan Kerman
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA
| | - Ben J Vernasco
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA
| | - Kendra B Sewall
- 2125 Derring Hall, Department of Biology, Virginia Tech, Blacksburg, VA 24061-0406, USA
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Davies S, Lane S, Meddle SL, Tsutsui K, Deviche P. The ecological and physiological bases of variation in the phenology of gonad growth in an urban and desert songbird. Gen Comp Endocrinol 2016; 230-231:17-25. [PMID: 26972152 PMCID: PMC4890648 DOI: 10.1016/j.ygcen.2016.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/09/2023]
Abstract
Birds often adjust to urban areas by advancing the timing (phenology) of vernal gonad growth. However, the ecological and physiological bases of this adjustment are unclear. We tested whether the habitat-related disparity in gonad growth phenology of male Abert's towhees, Melozone aberti, is due to greater food availability in urban areas of Phoenix, Arizona USA or, alternatively, a habitat-related difference in the phenology of key food types. To better understand the physiological mechanism underlying variation in gonad growth phenology, we compared the activity of the reproductive system at all levels of hypothalamo-pituitary-gonadal (HPG) axis. We found no habitat-associated difference in food availability (ground arthropod biomass), but, in contrast to the seasonal growth of leaves on desert trees, the leaf foliage of urban trees was already developed at the beginning of our study. Multiple estimates of energetic status did not significantly differ between the non-urban and urban towhees during three years that differed in the habitat-related disparity in gonad growth and winter precipitation levels. Thus, our results provide no support for the hypothesis that greater food abundance in urban areas of Phoenix drives the habitat-related disparity in gonad growth phenology in Abert's towhees. By contrast, they suggest that differences in the predictability and magnitude of change in food availability between urban and desert areas of Phoenix contribute to the observed habitat-related disparity in gonad growth. Endocrine responsiveness of the gonads may contribute to this phenomenon as desert - but not urban - towhees had a marked plasma testosterone response to GnRH challenge.
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Affiliation(s)
- Scott Davies
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
| | - Samuel Lane
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Simone L Meddle
- The Roslin Institute & Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9PS, UK
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo 162-8480, Japan
| | - Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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Valle S, Carpentier E, Vu B, Tsutsui K, Deviche P. Food restriction negatively affects multiple levels of the reproductive axis in male house finches, Haemorhous mexicanus. J Exp Biol 2015; 218:2694-704. [DOI: 10.1242/jeb.123323] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 06/23/2015] [Indexed: 01/06/2023]
Abstract
Nutrition influences reproductive functions across vertebrates, but the effects of food availability on the functioning of the hypothalamic-pituitary-gonadal (HPG) axis in wild birds and the mechanisms mediating these effects remain unclear. We investigated the influence of chronic food restriction on the HPG axis of photostimulated House Finches, Haemorhous mexicanus. Food-restricted birds had underdeveloped testes with smaller seminiferous tubules than ad libitum-fed birds. Baseline plasma testosterone (T) increased in response to photostimulation in ad libitum-fed but not in food-restricted birds. Food availability did not, however, affect the plasma T increase resulting from a gonadotropin-releasing hormone (GnRH) or a luteinizing hormone (LH) challenge. The number of hypothalamic GnRH-I immunoreactive (ir) but not proGnRH-ir perikarya was higher in food-restricted than ad libitum-fed finches, suggesting inhibited secretion of GnRH. Hypothalamic gonadotropin-inhibitory hormone (GnIH)-ir and neuropeptide Y (NPY)-ir were not affected by food availability. Plasma corticosterone (CORT) was also not affected by food availability, indicating that the observed HPG axis inhibition did not result from increased activity of the hypothalamic-pituitary-adrenal (HPA) axis. This study is among the first to examine multilevel functional changes in the HPG axis in response to food restriction in a wild bird. The results indicate that food availability affects both hypothalamic and gonadal function, but further investigations are needed to clarify the mechanisms by which nutritional signals mediate these effects.
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Affiliation(s)
- Shelley Valle
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Elodie Carpentier
- Universite de Poitiers, Faculté des Sciences Fondamentales et Appliquées, Poitiers, F-86022, France
| | - Bethany Vu
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Kazuyoshi Tsutsui
- Department of Biology, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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