-
International Journal of Biological... Jan 2024Histone acetylation, a crucial epigenetic mechanism, has been suggested to play a role in diapause regulation, but this has not been confirmed through gene...
Histone acetylation, a crucial epigenetic mechanism, has been suggested to play a role in diapause regulation, but this has not been confirmed through gene loss-of-function studies. In this work, we investigated the involvement of MYST family genes, which are key writers of histone acetylation, in initiating reproductive diapause using the cabbage beetle Colaphellus bowringi as a model. We identified C. bowringi orthologs of MYST, including Tip60, KAT6A, KAT7, and KAT8, from previous transcriptomes. Analyses of phylogenetic trees and protein domains indicated that these MYST proteins are structurally conserved across animal species. Expression of these MYST genes was found to be enriched in heads and ovaries of C. bowringi. Under reproductive photoperiod conditions, RNAi targeting MYST genes, especially KAT8, suppressed ovarian growth and yolk deposition, resembling the characteristics of diapausing ovaries. Additionally, KAT8 knockdown led to the upregulation of diapause-related genes, such as heat shock proteins and diapause protein 1, and the emergence of diapause-like guts. Moreover, KAT8 knockdown reduced the expression of a crucial enzyme involved in juvenile hormone (JH) biosynthesis, likely due to decreased H4K16ac levels. Consequently, our findings suggest that MYST family genes, specifically KAT8, influence the JH signal, thereby regulating the initiation of reproductive diapause.
Topics: Animals; Diapause, Insect; Histone Acetyltransferases; Phylogeny; Histones; Diapause; Coleoptera
PubMed: 38029912
DOI: 10.1016/j.ijbiomac.2023.128269 -
Journal of Insect Physiology Nov 2023Aphids adapt to unfavourable environmental conditions, such as low temperatures in winter, by laying diapausing eggs that overwinter. Diapause is a stress-resistant and...
Aphids adapt to unfavourable environmental conditions, such as low temperatures in winter, by laying diapausing eggs that overwinter. Diapause is a stress-resistant and developmentally arrested stage that can be adopted in order to increase the chance of survival in adverse environmental conditions. The diapause process of aphids is still very poorly understood. We followed the development of two species of aphids, Brachycorynella asparagi and Appendiseta robiniae, using the immunostained embryos of the aphids to identify mitotic cell divisions. Two different models of aphid diapause were demonstrated for the first time. In the first strategy, the embryo developed continuously during winter diapause, while in the second case, there was an embryonic arrest. The possibility of slow development of the whole body during diapause is a characteristic feature of aphids. The link to the plant's phenology appears to be a key factor in determining the diapause strategy in aphids.
PubMed: 37734703
DOI: 10.1016/j.jinsphys.2023.104569 -
Insect Molecular Biology Sep 2023Culex pipiens, the northern house mosquito, is a major vector of West Nile virus. To survive the severe winter, adult mosquitoes enter a diapause programme. Extended...
Culex pipiens, the northern house mosquito, is a major vector of West Nile virus. To survive the severe winter, adult mosquitoes enter a diapause programme. Extended lifespan and an increase in lipid storage are key indicators of diapause. Post-translational modifications to histone proteins impact the expression of genes and have been linked to the lifespan and energy utilisation of numerous insects. Here, we investigated the potential contribution of epigenetic alterations in initiating diapause in this mosquito species. Multiple sequence alignment of H3 sequences from other insect species demonstrates a high conservation of the H3 histone in Cx. pipiens throughout evolution. We then compared the levels of histone methylation in the ovaries and fat body tissues of diapausing and non-diapausing Cx. pipiens using western blots. Our data indicate that histone methylation levels in the ovaries of Cx. pipiens do not change during diapause. In contrast, H3K27me2 levels decrease more than twofold in the fat body of diapausing mosquitoes relative to non-diapausing counterparts. H3K27 methylation plays a crucial role in chromosome activation and inactivation during development in many insect species. This is predominantly governed by polycomb repressor complex 2. Intriguingly, a previous ChIP-seq study demonstrated that the transcription factor FOXO (Forkhead box O) targets the genes that comprise this complex. In addition, H3K27me2 exhibits dynamic abundance throughout the diapause programme in Cx. pipiens, suggesting its potential role in the initial activation of the diapause programme. This study expands our understanding of the relationship between alterations in epigenetic regulation and diapause.
PubMed: 37702080
DOI: 10.1111/imb.12871 -
Neotropical Entomology Oct 2023Megachile amparo (González, Revista Colombiana De Entomología 32(1):93-96, 2006) is the only high Andean leaf-cutter bee reported in Colombia and is possibly endemic...
Megachile amparo (González, Revista Colombiana De Entomología 32(1):93-96, 2006) is the only high Andean leaf-cutter bee reported in Colombia and is possibly endemic to the Colombian Andes. Although it is frequently observed, even in urban areas, its biology and ecology remain unknown. The present study aimed to describe detailed aspects of its bionomy. Trap-nests were installed on the Campus of the Nueva Granada University (Cajicá, Colombia) from June/2018 to March/2020. The trap-nests were wooden blocks (25 × 15 × 14 cm) with 30 cavities of Ø = 1 cm and different lengths (50 mm, 75 mm, and 100 mm) lined with waxed paper straws. During the observations, an increasing number of trap-nests were installed, increasing from 250 to 720 cavities. The trap-nests were monitored three times a week, recording both the date the start and end building by female. Most of the nest were maintained in the field to estimate the sex ratio, cell survival, and total development time under natural conditions. Thirty-two nests were removed at different times of the observation period to establish number of cells per nest, and cells built per female per day. We incubated 20 cells from different nests at 18 °C, 22 °C, 26 °C, and 32 °C to estimate the base temperature, thermal constant k (developmental time in degree days), and cell survival. Young cells of different positions were dissected and weighed to characterize food provision and brood cells. Computerized tomography-CT scans were performed in 30 brood cells to determine if diapause occurred during prepupal stage. Females nested 7- and 10-cm-long cavities and the number of cells per nest varied with cavity length. The brood cells had a length of 1.23 ± 0.12 cm and a diameter of 0.92 ± 0.05 cm. The female spends 1.17 ± 0.29 days to build a brood cell. Food provision varied according to the position of the brood cell in the nest. The adults of M. amparo present a marked seasonality being more active during dry months. Base temperature and thermal constant k were different for males and females. The sex ratio is female biased (1.9:1), and cell survival in the field was 89% with no cleptoparasites or predators recorded.
Topics: Humans; Male; Bees; Female; Animals; Nesting Behavior; Ecology; Food; Diapause; Sex Ratio
PubMed: 37369980
DOI: 10.1007/s13744-023-01061-1 -
Environmental Entomology Oct 2023This study investigated the effect of chilling temperature and duration on diapause termination in Eurytoma maslovskii, a major apricot pest in Korea and China. The...
This study investigated the effect of chilling temperature and duration on diapause termination in Eurytoma maslovskii, a major apricot pest in Korea and China. The experimental insects were sampled in mid-autumn. Overwintering larvae were subjected to a temperature range at -16, -4, 2, 9, 13 °C for 12 wk (a temperature of 19 °C was used for nonchilled control), and then exposed to cold temperature (2 °C) for different durations (from 1 to 16, 19, and 22 wk) at different times (20 September and 30 November) to determine adult emergence, prolonged larval diapause, and development rate postchilling. The results demonstrated a strong association between chilling temperature and duration with the emergence of E. maslovskii. It was observed that diapause may be terminated after at least 6 wk in the cold. However, the rate only reached a higher significance after 10 wk or longer duration of chilling. The optimal chilling temperature ranged from 2 to 9 °C. Late autumn chilling (mid-September) did not differ from winter chilling (late November). The postdiapause development rate of E. maslovskii was determined to be affected by the chilling duration and could be described by a 3-parameter probability density Weibull function. These results suggest that winter conditions play a crucial role in the phenology of E. maslovskii in spring.
PubMed: 37639697
DOI: 10.1093/ee/nvad087 -
Biological Reviews of the Cambridge... Jun 2024In biogeography, vicariance and long-distance dispersal are often characterised as competing scenarios. However, they are related concepts, both relying on collective... (Review)
Review
In biogeography, vicariance and long-distance dispersal are often characterised as competing scenarios. However, they are related concepts, both relying on collective geological, ecological, and phylogenetic evidence. This is illustrated by freshwater fishes, which may immigrate to islands either when freshwater connections are temporarily present and later severed (vicariance), or by unusual means when ocean gaps are crossed (long-distance dispersal). Marine barriers have a strong filtering effect on freshwater fishes, limiting immigrants to those most capable of oceanic dispersal. The roles of vicariance and dispersal are debated for freshwater fishes of the Greater Antilles. We review three active hypotheses [Cretaceous vicariance, Greater Antilles-Aves Ridge (GAARlandia), long-distance dispersal] and propose long-distance dispersal to be an appropriate model due to limited support for freshwater fish use of landspans. Greater Antillean freshwater fishes have six potential source bioregions (defined from faunal similarity): Northern Gulf of México, Western Gulf of México, Maya Terrane, Chortís Block, Eastern Panamá, and Northern South America. Faunas of the Greater Antilles are composed of taxa immigrating from many of these bioregions, but there is strong compositional disharmony between island and mainland fish faunas (>90% of Antillean species are cyprinodontiforms, compared to <10% in Northern Gulf of México and Northern South America, and ≤50% elsewhere), consistent with a hypothesis of long-distance dispersal. Ancestral-area reconstruction analysis indicates there were 16 or 17 immigration events over the last 51 million years, 14 or 15 of these by cyprinodontiforms. Published divergence estimates and evidence available for each immigration event suggests they occurred at different times and by different pathways, possibly with rafts of vegetation discharged from rivers or washed to sea during storms. If so, ocean currents likely provide critical pathways for immigration when flowing from one landmass to another. On the other hand, currents create dispersal barriers when flowing perpendicularly between landmasses. In addition to high salinity tolerance, cyprinodontiforms collectively display a variety of adaptations that could enhance their ability to live with rafts (small body size, viviparity, low metabolism, amphibiousness, diapause, self-fertilisation). These adaptations likely also helped immigrants establish island populations after arrival and to persist long term thereafter. Cichlids may have used a pseudo bridge (Nicaragua Rise) to reach the Greater Antilles. Gars (Lepisosteidae) may have crossed the Straits of Florida to Cuba, a relatively short crossing that is not a barrier to gene flow for several cyprinodontiform immigrants. Indeed, widespread distributions of Quaternary migrants (Cyprinodon, Gambusia, Kryptolebias), within the Greater Antilles and among neighbouring bioregions, imply that long-distance dispersal is not necessarily inhibitory for well-adapted species, even though it appears to be virtually impossible for all other freshwater fishes.
Topics: Animals; Fishes; Fresh Water; Animal Distribution; Phylogeography
PubMed: 38205676
DOI: 10.1111/brv.13050 -
Communications Biology Mar 2024Embryonic diapause in mammals is a temporary developmental delay occurring at the blastocyst stage. In contrast to other diapausing species displaying a full arrest, the...
Embryonic diapause in mammals is a temporary developmental delay occurring at the blastocyst stage. In contrast to other diapausing species displaying a full arrest, the blastocyst of the European roe deer (Capreolus capreolus) proliferates continuously and displays considerable morphological changes in the inner cell mass. We hypothesised that developmental progression also continues during this period. Here we evaluate the mRNA abundance of developmental marker genes in embryos during diapause and elongation. Our results show that morphological rearrangements of the epiblast during diapause correlate with gene expression patterns and changes in cell polarity. Immunohistochemical staining further supports these findings. Primitive endoderm formation occurs during diapause in embryos composed of around 3,000 cells. Gastrulation coincides with elongation and thus takes place after embryo reactivation. The slow developmental progression makes the roe deer an interesting model for unravelling the link between proliferation and differentiation and requirements for embryo survival.
Topics: Animals; Deer; Blastocyst; Cell Differentiation; Cell Polarity; Diapause
PubMed: 38443549
DOI: 10.1038/s42003-024-05944-w -
International Journal of Molecular... Dec 2023Diapause, an adaptative strategy for survival under harsh conditions, is a dynamic multi-stage process. , an important agricultural pollinator, is declining in the wild,...
Diapause, an adaptative strategy for survival under harsh conditions, is a dynamic multi-stage process. , an important agricultural pollinator, is declining in the wild, but artificial breeding is possible by imitating natural conditions. Mated queen bees enter reproductive diapause in winter and recover in spring, but the regulatory mechanisms remain unclear. Herein, we conducted a comparative 4D label-free proteomic analysis of queen bees during artificial breeding at seven timepoints, including pre-diapause, diapause, and post-diapause stages. Through bioinformatics analysis of proteomic and detection of substance content changes, our results found that, during pre-diapause stages, queen bees had active mitochondria with high levels of oxidative phosphorylation, high body weight, and glycogen and TAG content, all of which support energy consumption during subsequent diapause. During diapause stages, body weight and water content were decreased but glycerol increased, contributing to cold resistance. Dopamine content, immune defense, and protein phosphorylation were elevated, while fat metabolism, protein export, cell communication, signal transduction, and hydrolase activity decreased. Following diapause termination, JH titer, water, fatty acid, and pyruvate levels increased, catabolism, synaptic transmission, and insulin signaling were stimulated, ribosome and cell cycle proteins were upregulated, and cell proliferation was accelerated. Meanwhile, TAG and glycogen content decreased, and ovaries gradually developed. These findings illuminate changes occurring in queen bees at different diapause stages during commercial production.
Topics: Bees; Animals; Proteomics; Body Weight; Diapause; Glycogen; Water
PubMed: 38203496
DOI: 10.3390/ijms25010326 -
Nature Structural & Molecular Biology May 2024Dormancy is an essential biological process for the propagation of many life forms through generations and stressful conditions. Early embryos of many mammals are...
Dormancy is an essential biological process for the propagation of many life forms through generations and stressful conditions. Early embryos of many mammals are preservable for weeks to months within the uterus in a dormant state called diapause, which can be induced in vitro through mTOR inhibition. Cellular strategies that safeguard original cell identity within the silent genomic landscape of dormancy are not known. Here we show that the protection of cis-regulatory elements from silencing is key to maintaining pluripotency in the dormant state. We reveal a TET-transcription factor axis, in which TET-mediated DNA demethylation and recruitment of methylation-sensitive transcription factor TFE3 drive transcriptionally inert chromatin adaptations during dormancy transition. Perturbation of TET activity compromises pluripotency and survival of mouse embryos under dormancy, whereas its enhancement improves survival rates. Our results reveal an essential mechanism for propagating the cellular identity of dormant cells, with implications for regeneration and disease.
PubMed: 38783076
DOI: 10.1038/s41594-024-01313-7 -
Pest Management Science Jul 2024The ladybeetle, Coccinella septempunctata, an important predator, is widely used to control aphids, whiteflies, mites, thrips, and lepidopteran pests. Diapause control...
BACKGROUND
The ladybeetle, Coccinella septempunctata, an important predator, is widely used to control aphids, whiteflies, mites, thrips, and lepidopteran pests. Diapause control technology is key to extending C. septempunctata shelf-life and commercialization. Lipid accumulation is a major feature of reproductive diapause, but the function of AKH signaling as a regulator of lipid mobilization in reproductive diapause remains unclear. This study aimed to identify and characterize AKH and AKHR genes, and clarify their functions in reproductive diapause.
RESULTS
The relative expression levels of CsAKH and CsAKHR were the highest in the head and fat body, respectively, and were significantly decreased under diapause conditions, both in developmental stages and tissues (head, midgut, fat body, and ovary). Furthermore, CsAKH and CsAKHR expression was increased significantly after juvenile hormone (JH) injection, but CsMet silencing significantly inhibited CsAKH and CsAKHR expression, whereas CsMet knockdown blocked the induction effect of JH. CsAKH and CsAKHR knockdown significantly reduced water content, increased lipid storage, and promoted the expression of genes related to lipid synthesis, but significantly blocked ovarian development, and induced forkhead box O (FOXO) gene expression in C. septempunctata under reproduction conditions. By contrast, injection of AKH peptide significantly inhibited FOXO expression, reduced lipid storage, and increased water content in C. septempunctata under diapause conditions.
CONCLUSION
These results indicate that CsAKH and CsAKHR are involved in the regulation of lipid accumulation and ovarian development during diapause in C. septempunctata, and provide a promising target for manipulating C. septempunctata diapause. © 2024 Society of Chemical Industry.
Topics: Animals; Insect Hormones; Coleoptera; Pyrrolidonecarboxylic Acid; Insect Proteins; Diapause, Insect; Signal Transduction; Oligopeptides; Reproduction; Female; Lipid Metabolism
PubMed: 38459943
DOI: 10.1002/ps.8070