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The Journal of Experimental Biology Feb 2023Diapause, a stage-specific developmental arrest, is widely exploited by insects to bridge unfavorable seasons. Considerable progress has been made in understanding the...
Diapause, a stage-specific developmental arrest, is widely exploited by insects to bridge unfavorable seasons. Considerable progress has been made in understanding the ecology, physiology and evolutionary implications of insect diapause, yet intriguing questions remain. A more complete understanding of diapause processes on Earth requires a better geographic spread of investigations, including more work in the tropics and at high latitudes. Questions surrounding energy management and trade-offs between diapause and non-diapause remain understudied. We know little about how maternal effects direct the diapause response, and regulators of prolonged diapause are also poorly understood. Numerous factors that were recently linked to diapause are still waiting to be placed in the regulatory network leading from photoreception to engagement of the diapause program. These factors include epigenetic processes and small noncoding RNAs, and emerging data also suggest a role for the microbiome in diapause regulation. Another intriguing feature of diapause is the complexity of the response, resulting in a diverse suite of responses that comprise the diapause syndrome. Select transcription factors likely serve as master switches turning on these diverse responses, but we are far from understanding the full complexity. The richness of species displaying diapause offers a platform for seeking common components of a 'diapause toolbox'. Across latitudes, during invasion events and in a changing climate, diapause offers grand opportunities to probe evolutionary change and speciation. At a practical level, diapause responses can be manipulated for insect control and long-term storage. Diapausing insects also contain a treasure trove of pharmacological compounds and offer promising models for human health.
Topics: Humans; Animals; Diapause, Insect; Diapause; Biological Evolution; Climate; Ecology
PubMed: 36852692
DOI: 10.1242/jeb.245329 -
Methods in Molecular Biology (Clifton,... 2019The reproduction of the mink, Neovison vison, has been extensively studied over the past 70 years. The endocrine control of pregnancy is reasonably well understood, but...
The reproduction of the mink, Neovison vison, has been extensively studied over the past 70 years. The endocrine control of pregnancy is reasonably well understood, but our understanding of early embryo development is limited. The mink is one of the best characterized mammals for the study of embryonic diapause, but in order to unravel the complex interactions that occur between the blastocyst and the uterus during diapause and reactivation, a defined culture media system that supports growth is essential. Until recently, culture of the mink blastocyst has been relatively unsuccessful. This chapter will describe a method for successfully obtaining and culturing mink blastocysts and will highlight some of the unique challenges in working with this species. Methods to age match prediapause embryos in a mammal that exhibits superfetation, and to synchronize collection of reactivation from diapause stages using prolactin will be discussed. Finally, a quantitative method to determine the extent of cell proliferation in the blastocyst, a hallmark of reactivation from diapause, will be detailed.
Topics: Animals; Blastocyst; Diapause; Embryo Culture Techniques; Embryonic Development; Female; Mink; Prolactin
PubMed: 31230287
DOI: 10.1007/978-1-4939-9566-0_19 -
Scientific Reports Apr 2021The bivoltine strain of the domestic silkworm, Bombyx mori, has two generations per year. It shows a facultative diapause phenotype determined by environmental...
The bivoltine strain of the domestic silkworm, Bombyx mori, has two generations per year. It shows a facultative diapause phenotype determined by environmental conditions, including photoperiod and temperature, and nutrient conditions during embryonic and larval development of the mother. However, it remains unclear how the environmental signals received during development are selectively utilized as cues to determine alternative diapause phenotypes. We performed a comparative analysis between the Kosetsu strain of B. mori and a Japanese population of the wild mulberry silkworm B. mandarina concerning the hierarchical molecular mechanisms in diapause induction. Our results showed that for the Kosetsu, temperature signals during the mother's embryonic development predominantly affected diapause determination through the thermosensitive transient receptor potential ankyrin 1 (TRPA1) and diapause hormone (DH) signaling pathways. However, embryonic diapause in B. mandarina was photoperiod-dependent, although the DH signaling pathway and thermal sensitivity of TRPA1 were conserved within both species. Based on these findings, we hypothesize that TRPA1-activated signals are strongly linked to the signaling pathway participating in diapause induction in Kosetsu to selectively utilize the temperature information as the cue because temperature-dependent induction was replaced by photoperiodic induction in the TRPA1 knockout mutant.
Topics: Animals; Bombyx; Circadian Rhythm; Diapause; Gene Expression Regulation, Developmental; Morus; Phenotype; Photoperiod; Temperature
PubMed: 33850226
DOI: 10.1038/s41598-021-87590-4 -
Parasites & Vectors Jun 2017Mosquitoes are insects belonging to the order Diptera and family Culicidae. They are distributed worldwide and include approximately 3500 species, of which about 300... (Review)
Review
Mosquitoes are insects belonging to the order Diptera and family Culicidae. They are distributed worldwide and include approximately 3500 species, of which about 300 have medical and veterinary importance. The evolutionary success of mosquitoes, in both tropical and temperate regions, is due to the various survival strategies these insects have developed throughout their life histories. Of the many adaptive mechanisms, diapause and quiescence, two different types of dormancy, likely contribute to the establishment, maintenance and spread of natural mosquito populations. This review seeks to objectively and coherently describe the terms diapause and quiescence, which can be confused in the literature because the phenotypic effects of these mechanisms are often similar.
Topics: Animals; Biological Evolution; Cold Temperature; Culicidae; Diapause; Life Cycle Stages; Photoperiod; Tropical Climate
PubMed: 28651558
DOI: 10.1186/s13071-017-2235-0 -
Journal of Medical Entomology Sep 2016The invasion and range expansion of Aedes albopictus (Skuse) in North America represents an outstanding opportunity to study processes of invasion, range expansion, and... (Review)
Review
The invasion and range expansion of Aedes albopictus (Skuse) in North America represents an outstanding opportunity to study processes of invasion, range expansion, and climatic adaptation. Furthermore, knowledge obtained from such research is relevant to developing novel strategies to control this important vector species. Substantial evidence indicates that the photoperiodic diapause response is an important adaptation to climatic variation across the range of Ae. albopictus in North America. Photoperiodic diapause is a key determinant of abundance in both space and time, and the timing of entry into and exit out of diapause strongly affects seasonal population dynamics and thus the potential for arbovirus transmission. Emerging genomic technologies are making it possible to develop high-resolution, genome-wide genetic markers that can be used for genetic mapping of traits relevant to disease transmission and phylogeographic studies to elucidate invasion history. Recent work using next-generation sequencing technologies (e.g., RNA-seq), combined with physiological experiments, has provided extensive insight into the transcriptional basis of the diapause response in Ae. albopictus Applying this knowledge to identify novel targets for vector control represents an important future challenge. Finally, recent studies have begun to identify traits other than diapause that are affected by photoperiodism. Extending this work to identify additional traits influenced by photoperiod should produce important insights into the seasonal biology of Ae. albopictus.
Topics: Adaptation, Physiological; Aedes; Animals; Diapause, Insect; Introduced Species; Larva; North America; Photoperiod; Population Dynamics
PubMed: 27354438
DOI: 10.1093/jme/tjw037 -
Annual Review of Entomology Jan 2020Whole-animal experiments devised to investigate possible association between photoperiodic time measurement and the circadian system (Bünning's hypothesis) are compared... (Review)
Review
Whole-animal experiments devised to investigate possible association between photoperiodic time measurement and the circadian system (Bünning's hypothesis) are compared with more recent molecular investigations of circadian clock genes. In and some other species, experimental cycles of light and darkness revealed a photoperiodic oscillator, set to constant phase at dusk and measuring night length repeatedly during extended periods of darkness. In some species, however, extreme dampening revealed an unrepetitive (i.e., hourglass-like) response. Rhythms of clock gene transcript abundance may also show similar phase relationships to the light cycle, and gene silencing of important clock genes indicates that they play a crucial role in photoperiodism either alone or in concert. However, the multiplicity of peripheral oscillators in the insect circadian system indicates that more complex mechanisms might also be important.
Topics: Animals; Circadian Rhythm; Circadian Rhythm Signaling Peptides and Proteins; Diapause, Insect; Insecta; Photoperiod
PubMed: 31594413
DOI: 10.1146/annurev-ento-011019-025116 -
Cold Spring Harbor Protocols Feb 2023The African turquoise killifish is an emerging research organism known for its short life span and long-term diapause. Diapause is a unique dormant state that suspends...
The African turquoise killifish is an emerging research organism known for its short life span and long-term diapause. Diapause is a unique dormant state that suspends embryonic development without tradeoffs in the adulthood life span. Recently, diapause has been gaining increasing interest from the research community. Here, we report our methods for handling the embryos of that go through diapause. We focus on a few key steps: (1) collecting embryos, (2) sorting embryos entering diapause, (3) storing diapause embryos, (4) screening embryos exiting diapause, and (5) hatching post-diapause and fully developed embryos. This method should help the need to obtain a large number of embryos in synchronization with their diapause-entering and -exiting status and satisfy the need for cell biology, genetic, genomic, and biochemistry experiments.
Topics: Animals; Fundulidae; Cyprinodontiformes; Longevity; Diapause; Embryonic Development
PubMed: 36283839
DOI: 10.1101/pdb.prot107752 -
Developmental Biology Jul 2021Developmental plasticity refers the ability of an organism to adapt to various environmental stressors, one of which is nutritional stress. Caenorhabditis elegans... (Review)
Review
Developmental plasticity refers the ability of an organism to adapt to various environmental stressors, one of which is nutritional stress. Caenorhabditis elegans require various nutrients to successfully progress through all the larval stages to become a reproductive adult. If nutritional criteria are not satisfied, development can slow or completely arrest. In poor growth conditions, the animal can enter various diapause stages, depending on its developmental progress. In C. elegans, there are three well-characterized diapauses: the L1 arrest, the dauer diapause, and adult reproductive diapause, each associated with drastic changes in metabolism and germline development. At the centre of these changes is AMP-activated protein kinase (AMPK). AMPK is a metabolic regulator that maintains energy homeostasis, particularly during times of nutrient stress. Without AMPK, metabolism is disrupted during dauer, leading to the rapid consumption of lipid stores as well as misregulation of metabolic enzymes, leading to reduced survival. During the L1 arrest and dauer diapause, AMPK is responsible for ensuring germline quiescence by modifying the germline chromatin landscape to maintain germ cell integrity until conditions improve. Similar to classic hormonal signalling, small RNAs also play a critical role in regulating development and behaviour in a cell non-autonomous fashion. Thus, during the challenges associated with developmental plasticity, AMPK summons an army of signalling pathways to work collectively to preserve reproductive fitness during these periods of unprecedented uncertainty.
Topics: AMP-Activated Protein Kinases; Adaptation, Biological; Adaptation, Physiological; Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Diapause; Gene Expression Regulation, Developmental; Germ Cells; Larva; Nutrients; Signal Transduction; Stress, Physiological
PubMed: 33549550
DOI: 10.1016/j.ydbio.2021.01.015 -
BMC Biology Mar 2023Embryonic diapause (dormancy) is a state of temporary arrest of embryonic development that is triggered by unfavorable conditions and serves as an evolutionary strategy...
BACKGROUND
Embryonic diapause (dormancy) is a state of temporary arrest of embryonic development that is triggered by unfavorable conditions and serves as an evolutionary strategy to ensure reproductive survival. Unlike maternally-controlled embryonic diapause in mammals, chicken embryonic diapause is critically dependent on the environmental temperature. However, the molecular control of diapause in avian species remains largely uncharacterized. In this study, we evaluated the dynamic transcriptomic and phosphoproteomic profiles of chicken embryos in pre-diapause, diapause, and reactivated states.
RESULTS
Our data demonstrated a characteristic gene expression pattern in effects on cell survival-associated and stress response signaling pathways. Unlike mammalian diapause, mTOR signaling is not responsible for chicken diapause. However, cold stress responsive genes, such as IRF1, were identified as key regulators of diapause. Further in vitro investigation showed that cold stress-induced transcription of IRF1 was dependent on the PKC-NF-κB signaling pathway, providing a mechanism for proliferation arrest during diapause. Consistently, in vivo overexpression of IRF1 in diapause embryos blocked reactivation after restoration of developmental temperatures.
CONCLUSIONS
We concluded that embryonic diapause in chicken is characterized by proliferation arrest, which is the same with other spices. However, chicken embryonic diapause is strictly correlated with the cold stress signal and mediated by PKC-NF-κB-IRF1 signaling, which distinguish chicken diapause from the mTOR based diapause in mammals.
Topics: Animals; Chick Embryo; Female; Chickens; Diapause; NF-kappa B; Signal Transduction; Temperature; TOR Serine-Threonine Kinases
PubMed: 36882743
DOI: 10.1186/s12915-023-01550-0 -
International Journal of Molecular... Apr 2022Like many other insects in temperate regions, exploits the photoperiod shortening that occurs during the autumn as an important cue to trigger a seasonal response....
Like many other insects in temperate regions, exploits the photoperiod shortening that occurs during the autumn as an important cue to trigger a seasonal response. Flies survive the winter by entering a state of reproductive arrest (diapause), which drives the relocation of resources from reproduction to survival. Here, we profiled the expression of microRNA (miRNA) in long and short photoperiods and identified seven differentially expressed miRNAs (, , , , , , and ). Misexpression of , , and in pigment-dispersing, factor-expressing neurons largely disrupted the normal photoperiodic response, suggesting that these miRNAs play functional roles in photoperiodic timing. We also analyzed the targets of photoperiodic miRNA by both computational predication and by Argonaute-1-mediated immunoprecipitation of long- and short-day RNA samples. Together with global transcriptome profiling, our results expand existing data on other species, identifying genes and pathways that are differentially regulated in different photoperiods and reproductive status. Our data suggest that post-transcriptional regulation by miRNA is an important facet of photoperiodic timing.
Topics: Animals; Diapause; Drosophila; Drosophila melanogaster; MicroRNAs; Photoperiod
PubMed: 35563325
DOI: 10.3390/ijms23094935