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Foster RG. Introduction and reflections on the comparative physiology of sleep and circadian rhythms. J Comp Physiol B 2024:10.1007/s00360-024-01567-z. [PMID: 38856727 DOI: 10.1007/s00360-024-01567-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Accepted: 05/17/2024] [Indexed: 06/11/2024]
Abstract
Circadian rhythms and the sleep/wake cycle allows us, and most life on Earth, to function optimally in a dynamic world, adjusting all aspects of biology to the varied and complex demands imposed by the 24-hour rotation of the Earth upon its axis. A key element in understanding these rhythms, and the success of the field in general, has been because researchers have adopted a comparative approach. Across all taxa, fundamental questions relating to the generation and regulation of sleep and circadian rhythms have been address using biochemical, molecular, cellular, system and computer modelling techniques. Furthermore, findings have been placed into an ecological and evolutionary context. By addressing both the "How" - mechanistic, and "Why" - evolutionary questions in parallel, the field has achieved remarkable successes, including how circadian rhythms are generated and regulated by light. Yet many key questions remain. In this special issue on the Comparative Physiology of Sleep and Circadian Rhythms, celebrating the 100th anniversary of the Journal of Comparative Physiology, important new discoveries are detailed. These findings illustrate the power of comparative physiology to address novel questions and demonstrate that sleep and circadian physiology are embedded within the biological framework of an organism.
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Affiliation(s)
- Russell G Foster
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK.
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Liddle TA, Majumdar G, Stewart C, Bain MM, Stevenson TJ. Dissociating Mechanisms That Underlie Seasonal and Developmental Programs for the Neuroendocrine Control of Physiology in Birds. eNeuro 2024; 11:ENEURO.0154-23.2023. [PMID: 38548332 PMCID: PMC11007308 DOI: 10.1523/eneuro.0154-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 04/12/2024] Open
Abstract
Long-term programmed rheostatic changes in physiology are essential for animal fitness. Hypothalamic nuclei and the pituitary gland govern key developmental and seasonal transitions in reproduction. The aim of this study was to identify the molecular substrates that are common and unique to developmental and seasonal timing. Adult and juvenile quail were collected from reproductively mature and immature states, and key molecular targets were examined in the mediobasal hypothalamus (MBH) and pituitary gland. qRT-PCR assays established deiodinase type 2 (DIO2) and type 3 (DIO3) expression in adults changed with photoperiod manipulations. However, DIO2 and DIO3 remain constitutively expressed in juveniles. Pituitary gland transcriptome analyses established that 340 transcripts were differentially expressed across seasonal photoperiod programs and 1,189 transcripts displayed age-dependent variation in expression. Prolactin (PRL) and follicle-stimulating hormone subunit beta (FSHβ) are molecular markers of seasonal programs and are significantly upregulated in long photoperiod conditions. Growth hormone expression was significantly upregulated in juvenile quail, regardless of photoperiodic condition. These findings indicate that a level of cell autonomy in the pituitary gland governs seasonal and developmental programs in physiology. Overall, this paper yields novel insights into the molecular mechanisms that govern developmental programs and adult brain plasticity.
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Affiliation(s)
- Timothy Adam Liddle
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Gaurav Majumdar
- Department of Zoology, University of Allahabad, Allahabad, India
| | - Calum Stewart
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Maureen M Bain
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Tyler John Stevenson
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
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Chang J, Xu Y, Fu Y, Liu J, Jiang D, Pan J, Ouyang H, Liu W, Xu J, Tian Y, Huang Y, Ruan J, Shen X. The dynamic landscape of chromatin accessibility and active regulatory elements in the mediobasal hypothalamus influences the seasonal activation of the reproductive axis in the male quail under long light exposure. BMC Genomics 2024; 25:197. [PMID: 38373887 PMCID: PMC10877898 DOI: 10.1186/s12864-024-10097-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 02/07/2024] [Indexed: 02/21/2024] Open
Abstract
BACKGROUND In cold and temperate zones, seasonal reproduction plays a crucial role in the survival and reproductive success of species. The photoperiod influences reproductive processes in seasonal breeders through the hypothalamic-pituitary-gonadal (HPG) axis, in which the mediobasal hypothalamus (MBH) serves as the central region responsible for transmitting light information to the endocrine system. However, the cis-regulatory elements and the transcriptional activation mechanisms related to seasonal activation of the reproductive axis in MBH remain largely unclear. In this study, an artificial photoperiod program was used to induce the HPG axis activation in male quails, and we compared changes in chromatin accessibility changes during the seasonal activation of the HPG axis. RESULTS Alterations in chromatin accessibility occurred in the mediobasal hypothalamus (MBH) and stabilized at LD7 during the activation of the HPG axis. Most open chromatin regions (OCRs) are enriched mainly in introns and distal intergenic regions. The differentially accessible regions (DARs) showed enrichment of binding motifs of the RFX, NKX, and MEF family of transcription factors that gained-loss accessibility under long-day conditions, while the binding motifs of the nuclear receptor (NR) superfamily and BZIP family gained-open accessibility. Retinoic acid signaling and GTPase-mediated signal transduction are involved in adaptation to long days and maintenance of the HPG axis activation. According to our footprint analysis, three clock-output genes (TEF, DBP, and HLF) and the THRA were the first responders to long days in LD3. THRB, NR3C2, AR, and NR3C1 are the key players associated with the initiation and maintenance of the activation of the HPG axis, which appeared at LD7 and tended to be stable under long-day conditions. By integrating chromatin and the transcriptome, three genes (DIO2, SLC16A2, and PDE6H) involved in thyroid hormone signaling showed differential chromatin accessibility and expression levels during the seasonal activation of the HPG axis. TRPA1, a target of THRB identified by DAP-seq, was sensitive to photoactivation and exhibited differential expression levels between short- and long-day conditions. CONCLUSION Our data suggest that trans effects were the main factors affecting gene expression during the seasonal activation of the HPG axis. This study could lead to further research on the seasonal reproductive behavior of birds, particularly the role of MBH in controlling seasonal reproductive behavior.
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Affiliation(s)
- Jianye Chang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Yanglong Xu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yuting Fu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Jiaxin Liu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Danli Jiang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Jianqiu Pan
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Hongjia Ouyang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Wenjun Liu
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Jin Xu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510642, China
| | - Yunbo Tian
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yunmao Huang
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China.
| | - Jue Ruan
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China.
| | - Xu Shen
- College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China.
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Marchese NA, Ríos MN, Guido ME, Valdez DJ. Three different seasonally expressed opsins are present in the brain of the Eared Dove, an opportunist breeder. ZOOLOGY 2024; 162:126147. [PMID: 38277721 DOI: 10.1016/j.zool.2024.126147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 09/01/2023] [Accepted: 01/12/2024] [Indexed: 01/28/2024]
Abstract
Birds living at high latitudes perceive the photoperiod through deep-brain photoreceptors (DBP) located in deep-brain neurons. During long photoperiods the information transmitted by these photoreceptors increases the activity of the hypothalamic-pituitary-gonadal (HPG) axis, leading to gonadal development. The presence of photopigments such as VA-Opsin, Opn4, Opn5 and Opn2 in brain areas implicated in reproductive behaviors has been firmly established in several avian species with seasonal breeding, whereas their existence in opportunistic breeding birds remains unconfirmed. The Eared Dove is an urban and peri-urban dove that breeds throughout the year. Males of this species do not exhibit the typical gonadal regression/recrudescence cycle, thus posing the question of what occurs upstream of the HPG axis. We addressed this issue by first studying the presence of diverse opsins located in DBP in the brains of Eared Dove males and whether these photopigments changed their expression throughout the year. We carried out an immunohistochemistry analysis on three different opsins: Opn2 (rhodopsin), Opn3 and Opn5. Our results demonstrate the discrete neuroanatomical distribution of these opsins in the brain of Eared Dove males and strongly indicate different seasonal expressions. In the anterior region of the hypothalamus, Opn2-positive cells were detected throughout the year. By contrast, Opn5 was found to be strongly and seasonally expressed during winter in the anterior and the hypothalamic region. Opn3 was also found to be significantly and seasonally expressed during winter in the hypothalamic region. We thus demonstrate for the first time that males of the Eared Dove, have three different deep-brain opsin-expressing photoreceptors with differential location/distribution in the anterior and hypothalamic region and differential seasonality. The persistence of Opn2 and the strong seasonal expression of nonvisual photopigments Opn3 and Opn5 in two areas of the avian brain, which are associated with reproduction, could be the primary distinction between seasonal and opportunistic breeders.
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Affiliation(s)
- Natalia A Marchese
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Departamento de Química Biológica "Ranwel Caputto" Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maximiliano N Ríos
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Departamento de Química Biológica "Ranwel Caputto" Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Mario E Guido
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Departamento de Química Biológica "Ranwel Caputto" Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Diego J Valdez
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Zoología Aplicada, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina.
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Majumdar G, Yadav G, Singh NS. Photoperiodic physiology of summer breeding birds and a search for the role of eye. Photochem Photobiol Sci 2024; 23:197-212. [PMID: 38038950 DOI: 10.1007/s43630-023-00505-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023]
Abstract
Photoperiod regulation of gonadal cycles is well studied and documented in both birds and mammals. Change in photoperiod is considered as the most effective and important cue to time the initiation of the annual physiological cycles in birds. Approaching of long days (as observed in summer months), signal long-day breeding birds to initiation reproduction and other related functions. Birds and other non-mammalian vertebrates use the extraocular photoreceptors which may be present in the mediobasal hypothalamus (MBH) or associated regions to measure the photoperiodic time and so are different from mammals where only the eyes are lone photoreceptive organs. The downstream signaling involves thyroid responsive genes playing a crucial role in mediating photoperiodic signals in both birds and mammals. Role of eyes in the avian seasonal cycle has been a questionable issue with evidences both favoring and negating any role. We propose that morphological as well as physiological data argue that retinal photoreceptors can participate in gonadal cycle, at least in the quail and duck. The present review details the studies of photoneuroendocrine control of gonadal axis in birds and review evidences to decipher the role eyes in photoperiodic mediated physiologies in birds.
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Affiliation(s)
- Gaurav Majumdar
- Department of Zoology, University of Allahabad, Prayagraj, Uttar Pradesh, 211002, India
| | - Garima Yadav
- Department of Biochemistry, University of Allahabad, Prayagraj, Uttar Pradesh, 211002, India
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Grunst ML, Grunst AS. Endocrine effects of exposure to artificial light at night: A review and synthesis of knowledge gaps. Mol Cell Endocrinol 2023; 568-569:111927. [PMID: 37019171 DOI: 10.1016/j.mce.2023.111927] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/26/2023] [Accepted: 03/29/2023] [Indexed: 04/07/2023]
Abstract
Animals have evolved with natural patterns of light and darkness, such that light serves as an important zeitgeber, allowing adaptive synchronization of behavior and physiology to external conditions. Exposure to artificial light at night (ALAN) interferes with this process, resulting in dysregulation of endocrine systems. In this review, we evaluate the endocrine effects of ALAN exposure in birds and reptiles, identify major knowledge gaps, and highlight areas for future research. There is strong evidence for ecologically relevant levels of ALAN acting as an environmental endocrine disruptor. However, most studies focus on the pineal hormone melatonin, corticosterone release via the hypothalamus-pituitary-adrenal axis, or regulation of reproductive hormones via the hypothalamus-pituitary-gonadal axis, leaving effects on other endocrine systems largely unknown. We call for more research spanning a diversity of hormonal systems and levels of endocrine regulation (e.g. circulating hormone levels, receptor numbers, strength of negative feedback), and investigating involvement of molecular mechanisms, such as clock genes, in hormonal responses. In addition, longer-term studies are needed to elucidate potentially distinct effects arising from chronic exposure. Other important areas for future research effort include investigating intraspecific and interspecific variability in sensitivity to light exposure, further distinguishing between distinct effects of different types of light sources, and assessing impacts of ALAN exposure early in life, when endocrine systems remain sensitive to developmental programming. The effects of ALAN on endocrine systems are likely to have a plethora of downstream effects, with implications for individual fitness, population persistence, and community dynamics, especially within urban and suburban environments.
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Affiliation(s)
- Melissa L Grunst
- Littoral, Environnement et Sociétés (LIENS), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, FR-17000, La Rochelle, France.
| | - Andrea S Grunst
- Littoral, Environnement et Sociétés (LIENS), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, FR-17000, La Rochelle, France
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Karthikeyan R, Davies WI, Gunhaga L. Non-image-forming functional roles of OPN3, OPN4 and OPN5 photopigments. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2023. [DOI: 10.1016/j.jpap.2023.100177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
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