Cell cycle arrest in the jewel wasp Nasonia vitripennis in larval diapause (original) (raw)
Related papers
Insect Biochemistry and Molecular Biology, 2009
The division cycle of CNS cells was arrested in G0/G1 (86.6%) and G2 (12.8%) phases in diapausing larvae of Chymomyza costata. A two-step response was observed when the diapause was induced by transferring the 3rd instar larvae from long-day to short-day conditions: first, the proportion of G2-arrested cells increased rapidly within a single day after transfer; and second, the increase of G0/G1-arrested cells started with a delay of 5 days after transfer. The changes of relative mRNA levels of seven different genes, which code for important cell cycle regulatory factors [Cyclins D and E, kinases Wee1 and Myt1, phosphatase Cdc25 (String), Dacapo (p27), and PCNA] were followed using qRT-PCR technique. Two reference genes (Rp49 and ß-tubulin) served as a background. Significant transcriptional responses to photoperiodic transfer were observed for two genes: while the relative levels of dacapo mRNA increased during the rapid entry into the G2 arrest, the pcna expression was significantly downregulated during the delayed onset of G0/G1 arrest. In addition, moderate transcriptional upregulations of the genes coding for two inhibitory kinases, wee1 and myt1 accompanied the entry into diapause. The other genes were expressed equally in all photoperiodic conditions.
Applied Entomology and Zoology
The role of the clock gene period (per) in photoperiodism was investigated in the jewel wasp Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae). Typically, females reared under long days lay eggs that develop to adulthood without developmental interruption, whereas those reared under short days lay eggs that enter larval diapause. We found that RNA interference (RNAi) of per disrupts the photoperiodic response; RNAi wasps failed to produce diapause-destined eggs in response to short days. This indicates that per is essential for the photoperiodic response in this species. Exposure to low temperature swiftly affects maternal physiology and prompts N. vitripennis females to lay diapause-destined eggs. Interestingly, per RNAi females also laid diapause-destined eggs in response to the low temperature treatment in the current study. This finding indicates that per RNAi did not disrupt the maternal physiology that was directly involved in production of diapause-destined eggs, but it did affect photoperiodic perception. We also investigated the expression patterns of several clock genes, per, mammalian-type cryptochrome (cry-m), cycle (cyc), PAR domain protein 1 (Pdp1), and clockwork orange (cwo), to determine whether their expression patterns were affected by different photoperiods.
Diapause-specific gene expression in pupae of the flesh fly Sarcophaga crassipalpis
Proceedings of the National Academy of Sciences, 1998
Several cDNAs isolated from brains of diapausing pupae of the f lesh f ly, Sarcophaga crassipalpis, show expression patterns unique to diapause. To isolate such cDNAs a diapause pupal brain cDNA library was screened by using an elimination hybridization technique, and cDNAs that did not hybridize with cDNA probes constructed from the RNA of nondiapausing pupae were selected for further screening. The 95 clones that did not hybridize in the initial library screen were selected for further characterization. These clones were then screened against diapause and nondiapause pupal poly(A) ؉ Northern blots. The secondary screen identified 4 diapause-up-regulated clones, 7 diapause-down-regulated clones, 8 clones expressed equally in both diapause and nondiapause, and 75 clones without detectable expression. The diapause-up-regulated and down-regulated clones were further characterized by partial DNA sequencing and identity searches by using GenBank. Identities between our cloned cDNAs and other genes included those linked to cell cycle progression, stress responses, and DNA repair processes. The results suggest that insect diapause is not merely a shutdown of gene expression but is a unique, developmental pathway characterized by the expression of a novel set of genes.
Innate immune system still works at diapause, a physiological state of dormancy in insects
Biochemical and Biophysical Research Communications, 2011
Diapause is most often observed in insects and is a physiologically dormant state different from other types of dormancy, such as hibernation. It allows insects to survive in harsh environments or extend longevity. In general, larval, pupal, or adult non-diapausing insects possess an innate immune system preventing the invasion of microorganisms into their bodies; however, it is unclear whether this system works under the dormant condition of diapause. We here report the occurrence of innate cellular reactions during diapause using pupae of a giant silkmoth, Samia cynthia pryeri. Scanning electron microscopic analysis demonstrated the presence of two major types of cells in the body fluid isolated from the thoracic region of a pupa. Phagocytosis and encapsulation, characteristics of innate cellular reactions, by these cells were observed when latex beads as foreign targets were microinjected into the internal portion of a pupa. Such behavior by these cells was still observed even when pupae were continuously chilled at 4°C. Our results indicate that innate cellular reactions can work in diapausing insects in a dormant state.
Archives of Insect Biochemistry and Physiology, 2011
When treated with the steroid hormone 20-hydroxyecdysone (20E), C7-10 cells from the mosquito, Aedes albopictus, arrest in the G1 phase of the cell cycle. To explore whether 20Emediated cell cycle arrest proceeds through increased levels of cell cycle inhibitor (CKI) proteins, we cloned the Ae. albopictus homolog of dacapo, the single member of the Cip/Kip family of CKI proteins known from Drosophila melanogaster. The Ae. albopictus dacapo cDNA encoded a 261amino acid homolog of the Aedes aegypti protein XP_001651102.1, which is encoded by an ~23 kb gene containing three exons. Like dacapo from D. melanogaster, the ~27 kDa protein from Aedes and Culex mosquitoes contained several S/TXXE/D motifs corresponding to potential protein kinase CK2 phosphorylation sites, and a binding site for proliferating cell nuclear antigen (PCNA). When extracts from cells treated with 20E were analyzed by western blotting, using a primary antibody to synthetic peptides from the mosquito dacapo protein, up-regulation of an ~27 kDa protein was observed within 24 h, and the abundance of the protein further increased by 48 h after hormone treatment. This is the first investigation of a cell cycle inhibitory protein in mosquitoes. The results reinforce growing evidence that 20E affects expression of proteins that regulate cell cycle progression.
Philosophical Transactions of the Royal Society B: Biological Sciences
The exceptional longevity of social insect queens despite their lifelong high fecundity remains poorly understood in ageing biology. To gain insights into the mechanisms that might underlie ageing in social insects, we compared gene expression patterns between young and old castes (both queens and workers) across different lineages of social insects (two termite, two bee and two ant species). After global analyses, we paid particular attention to genes of the insulin/insulin-like growth factor 1 signalling (IIS)/target of rapamycin (TOR)/juvenile hormone (JH) network, which is well known to regulate lifespan and the trade-off between reproduction and somatic maintenance in solitary insects. Our results reveal a major role of the downstream components and target genes of this network (e.g. JH signalling, vitellogenins, major royal jelly proteins and immune genes) in affecting ageing and the caste-specific physiology of social insects, but an apparently lesser role of the upstream IIS...
Journal of Insect Physiology, 2005
Distinct differences in the temporal expression patterns of genes associated with pupal diapause were noted in the flesh fly, Sarcophaga crassipalpis. The first change observed was a decline in expression of the gene encoding heat shock protein 90 (hsp90) 2 days after pupariation (1 day before the pupa reaches the phanerocephalic stage characteristic of diapause). In contrast, hsp23 and hsp70 transcripts were undetectable in nondiapause samples and d1-d4 diapause-programmed pupae, but were up-regulated just after the start of diapause, 5 days after pupariation. An increase of glycerol content in diapausing pupae was also noted at the start of diapause. The gene encoding proliferating cell nuclear antigen (pcna) was diapause down-regulated, and this occurred in two phases, with the first decline in expression 7 days after pupariation and a second decline in the level of expression on day 14. For pupae held at 20 1C for 20 days and transferred to 10 1C, diapause ended after 90-100 days at the lower temperature. However, pupae remained in a state of post-diapause quiescence (d100-d150) and sustained diapause-like hsp and pcna expression patterns until adult development was initiated. Glycerol concentrations and survival declined during the post-diapause phase. This study suggests a distinct sequence in the pattern of gene expression at the onset of diapause, but the genes we have monitored do not contribute to the switch to covert developmental potential at the transition from diapause to post-diapause quiescence. r
Insect Biochemistry and Molecular Biology, 2016
The growing appreciation that epigenetic processes are integral to the responses of many organisms to changes in the environment suggests a possible role for epigenetics in coordination of insect diapause. The results we present suggest that histone modification may be one type of epigenetic process that contributes to regulation of pupal diapause in the flesh fly, Sarcophaga bullata. Reduction in total histone H3 acetylation in diapausing pupae, shifts in mRNA expression profiles of genes encoding histone acetyltransferase (HAT) and histone deacetylase (HDAC) in pre-diapause, diapause and post-diapause flies compared to their nondiapause counterparts, and alterations in HDAC enzyme activity during and post-diapause lend support to the hypothesis that this specific type of histone modification is involved in regulating diapause programming, maintenance, and termination. Transcription of genes encoding HDAC1, HDAC3, HDAC6, and Sirtuin2 were all upregulated in photosensitive first instar larvae programmed to enter pupal diapause, suggesting that histone deacetylation may be linked to the early decision to enter diapause. A 50% reduction in transcription of hdac3 and a corresponding 30% reduction in HDAC activity during diapause suggest that removal of acetyl groups from histones primarily occurs prior to diapause entry and that further histone deacetylation is not necessary to maintain diapause. Transcription of the HDAC genes was quickly elevated when diapause was terminated, followed by an increase in enzyme activity after a short delay. A maternal effect operating in these flies prevents pupal diapause in progeny whose mothers experienced pupal diapause, even if the progeny are reared in strong diapause-inducing short-day conditions. Such nondiapausing pupae had HDAC transcription profiles nearly identical to the profiles seen in nondiapausing pupae generated under a longday photoperiod. Together, these results provide consistent evidence for histone acetylation and deacetylation as regulators of this insect's developmental trajectory.