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Current Opinion in Insect Science Dec 2019Diapause in response to seasonality is an important model for rapid evolutionary adaptation that is highly genetically variable, and experiences strong natural... (Review)
Review
Diapause in response to seasonality is an important model for rapid evolutionary adaptation that is highly genetically variable, and experiences strong natural selection. Forward genetic methods using various genomic and transcriptomic approaches have begun to characterize the genetic architecture and candidate genes underlying diapause evolution. Largely in parallel, reverse genetic studies have identified functional roles for candidate genes that may or may not be genetically variable. We illustrate the disconnect between the evolutionary and physiological literature using a suite of studies of the role of the circadian clock in diapause regulation. These extensive studies in two different disciplines provide excellent opportunities for integration, which should facilitate rapid progress in understanding both the regulation and evolution of diapause.
Topics: Animals; Biological Evolution; Circadian Clocks; Diapause, Insect; Insecta; Seasons
PubMed: 31539788
DOI: 10.1016/j.cois.2019.08.003 -
Journal of Assisted Reproduction and... May 2020
Topics: Animals; Diapause; Embryo, Mammalian; Fertilization; Humans
PubMed: 32248337
DOI: 10.1007/s10815-020-01766-x -
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 -
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 -
Proceedings of the National Academy of... Dec 2022Diapause is a form of dormancy used widely by insects to survive adverse seasons. Previous studies have demonstrated that forkhead box O (FoxO) is activated during pupal...
Diapause is a form of dormancy used widely by insects to survive adverse seasons. Previous studies have demonstrated that forkhead box O (FoxO) is activated during pupal diapause initiation in the moth . However, it is unclear how FoxO induces diapause. Here, we show that knockout of causes diapause-destined pupae to channel into nondiapause, indicating that FoxO is a master regulator that induces insect diapause. FoxO activates the ubiquitin-proteasome system (UPS) by promoting ubiquitin c (Ubc) expression via directly binding to the promoter. Activated UPS decreases transforming growth factor beta (TGFβ) receptor signaling via ubiquitination to block developmental signaling to induce diapause. This study significantly advances the understanding of insect diapause by uncovering the detailed molecular mechanism of FoxO.
Topics: Animals; Transforming Growth Factor beta; Pupa; Diapause; Signal Transduction; Diapause, Insect; Receptors, Transforming Growth Factor beta; Ubiquitin; Proteasome Endopeptidase Complex
PubMed: 36442095
DOI: 10.1073/pnas.2210404119 -
BMC Genomics Jun 2021Diapause is a seasonal dormancy that allows organisms to survive unfavorable conditions and optimizes the timing of reproduction and growth. Emergence from diapause...
BACKGROUND
Diapause is a seasonal dormancy that allows organisms to survive unfavorable conditions and optimizes the timing of reproduction and growth. Emergence from diapause reverses the state of arrested development and metabolic suppression returning the organism to an active state. The physiological mechanisms that regulate the transition from diapause to post-diapause are still unknown. In this study, this transition has been characterized for the sub-arctic calanoid copepod Neocalanus flemingeri, a key crustacean zooplankter that supports the highly productive North Pacific fisheries. Transcriptional profiling of females, determined over a two-week time series starting with diapausing females collected from > 400 m depth, characterized the molecular mechanisms that regulate the post-diapause trajectory.
RESULTS
A complex set of transitions in relative gene expression defined the transcriptomic changes from diapause to post-diapause. Despite low temperatures (5-6 °C), the switch from a "diapause" to a "post-diapause" transcriptional profile occurred within 12 h of the termination stimulus. Transcriptional changes signaling the end of diapause were activated within one-hour post collection and included the up-regulation of genes involved in the 20E cascade pathway, the TCA cycle and RNA metabolism in combination with the down-regulation of genes associated with chromatin silencing. By 12 h, females exhibited a post-diapause phenotype characterized by the up-regulation of genes involved in cell division, cell differentiation and multiple developmental processes. By seven days post collection, the reproductive program was fully activated as indicated by up-regulation of genes involved in oogenesis and energy metabolism, processes that were enriched among the differentially expressed genes.
CONCLUSIONS
The analysis revealed a finely structured, precisely orchestrated sequence of transcriptional changes that led to rapid changes in the activation of biological processes paving the way to the successful completion of the reproductive program. Our findings lead to new hypotheses related to potentially universal mechanisms that terminate diapause before an organism can resume its developmental program.
Topics: Animals; Arctic Regions; Copepoda; Diapause; Female; Reproduction; Transcriptome
PubMed: 34082716
DOI: 10.1186/s12864-021-07557-7 -
Theriogenology Dec 2020An alarming number of large mammalian species with low reproduction rates is threatened with extinction. As basic knowledge of reproductive physiology is currently... (Review)
Review
An alarming number of large mammalian species with low reproduction rates is threatened with extinction. As basic knowledge of reproductive physiology is currently lacking in many species, increasing the understanding of reproductive physiology is imperative and includes the development of novel artificial reproduction technologies. Despite the relatively comprehensive knowledge on molecular mechanisms underlying reproduction in livestock species such as cattle, pregnancy failures are likewise far from understood. Contrary to other wildlife species, the European roe deer (Capreolus capreolus) displays a remarkably high pregnancy rate. In parts, cattle and roe deer exhibit comparable features of preimplantation embryo development. Therefore, understanding the high fertility rate in the roe deer holds a great potential for cross-species knowledge gain. As the only known species among the artiodactylae, the roe deer displays a long period of embryonic diapause. The preimplantation blastocyst reaches a diameter of 1 mm only at around 4 months compared to around 13 days post estrus in cattle. The expanded blastocyst survives in a uterine microenvironment that contains a unique set of yet unidentified factors that allow embryonic stem cells to proliferate at low pace without impairing their developmental potential. Upon reactivation, intimate embryo-maternal communication comparable to those reported in cattle is thought to occur. In this review, current knowledge, parallels and differences of reproductive physiology in cattle and roe deer are reviewed. The roe deer is proposed as a unique model species to (1) enhance our knowledge of fertility processes, (2) define factors that support embryo survival for an extended period, (3) advance knowledge on embryonic stem cells, and (4) unravel potential implications for the development of novel strategies for artificial reproductive technologies.
Topics: Animals; Animals, Wild; Cattle; Communication; Deer; Diapause; Embryonic Development; Female; Livestock; Pregnancy
PubMed: 32947063
DOI: 10.1016/j.theriogenology.2020.06.042 -
Zoological Science Apr 2024The silkworm exhibits a photoperiodic response (PR) for embryonic diapause induction. This article provides a comprehensive review of literature on the silkworm PR,... (Review)
Review
The silkworm exhibits a photoperiodic response (PR) for embryonic diapause induction. This article provides a comprehensive review of literature on the silkworm PR, starting from early works on population to recent studies uncovering the molecular mechanism. Makita Kogure (1933) conducted extensive research on the PR, presenting a pioneering paper on insect photoperiodism. In the 1970s and 80s, artificial diets were developed, and the influence of nutrition on PR was well documented. The photoperiodic photoreceptor has been investigated from organ to molecular level in the silkworm. Culture experiments demonstrated that the photoperiodic induction can be programmed in an isolated brain (Br)-subesophageal ganglion (SG) complex with corpora cardiaca (CC)-corpora allata (CA). The requirement of dietary vitamin A for PR suggests the involvement of opsin pigment in the photoperiodic reception, and a cDNA encoding an opsin (Boceropsin) was cloned from the brain. The effector system concerning the production and secretion of diapause hormone (DH) has also been extensively investigated in the silkworm. DH is produced in a pair of posterior cells of SG, transported to CC by nervi corporis cardiaci, and ultimately released into the hemolymph. Possible involvement of GABAergic and corazonin (Crz) signal pathways was suggested in the control of DH secretion. Knockout (KO) experiments of GABA transporter () and circadian clock genes demonstrated that GAT plays a crucial role in PR through circadian control. A model outlining the PR mechanism, from maternal photoperiodic light reception to DH secretion, has been proposed.
Topics: Animals; Bombyx; DNA, Complementary; Ganglia; Diapause; Opsins; Diapause, Insect
PubMed: 38587909
DOI: 10.2108/zs230036 -
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 -
Journal of Insect Science (Online) Jan 2021The western tarnished plant bug, Lygus hesperus Knight, overwinters as a diapausing adult in response to short day lengths. Once environmental conditions are favorable,...
The western tarnished plant bug, Lygus hesperus Knight, overwinters as a diapausing adult in response to short day lengths. Once environmental conditions are favorable, the bugs revert to an active reproductive state. To determine the impact on life-history traits of diverting resources toward diapause rather than oogenesis during early adulthood, diapausing and nondiapausing L. hesperus females were reared from the same cohorts. Body mass, ovarian maturation, ovipositional activity, and survivorship were monitored starting either at the time of release from diapause-inducing conditions or at adult eclosion for diapausers and nondiapausers, respectively. Females that had gone through 2 wk of diapause were larger and able to mobilize the resources necessary for oogenesis faster than nondiapausers, initiating oogenesis and ovipositing sooner and at a faster initial rate. However, lifetime egg production and average daily rates were similar for both groups. Postdiapausers lived longer than nondiapausers by an average of 19 d, which is five more than the 2-wk period when they were reproductively senescent. Overall, the results indicate that short-term diapause does not have a negative impact on life history. Furthermore, the extra endogenous resources stored during diapause may be able to enhance the alacrity with which the female can take advantage of improved environmental conditions and may prolong life by shielding the females against environmental stressors such as temperature extremes, oxidative agents, or food deficits.
Topics: Animals; Diapause, Insect; Female; Heteroptera; Life History Traits; Oogenesis; Oviposition
PubMed: 33400796
DOI: 10.1093/jisesa/ieaa142