| 1. |
- Keehnen, Naomi, et al.
(författare)
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Geographic variation in hemocyte diversity and phagocytic propensity shows a diffuse genomic signature in the green veined white butterfly
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Insects rely on their innate immune system to successfully mediate complex interactions with their internal microbiota, as well as the microbes present in the environment. Given the variation in microbes across habitats, the challenges to respond to them is likely to result in local adaptation in the immune system. Here we focus upon phagocytosis, a mechanism by which pathogens and foreign particles are engulfed in order to be contained, killed and processed for antigen presentation. We investigated the phenotypic and genetic variation related to phagocytosis, in two allopatric populations of the butterfly Pieris napi. We found that the populations differ in their hemocyte composition, and overall phagocytic capability, driven by the increased phagocytic propensity of each cell type. However, no evidence for divergence in phagocytosis-related genes was observed, though an enrichment of genes involved in glutamine metabolism was found, which have recently been linked to immune cell differentiation in mammals.
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| 2. |
- Keehnen, Naomi L.P., et al.
(författare)
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A Population Genomic Investigation of Immune Cell Diversity and Phagocytic Capacity in a Butterfly
- 2021
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Ingår i: Genes. - : MDPI AG. - 2073-4425 .- 2073-4425. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Insects rely on their innate immune system to successfully mediate complex interactions with their internal microbiota, as well as the microbes present in the environment. Given the variation in microbes across habitats, the challenges to respond to them are likely to result in local adaptations in the immune system. Here we focus upon phagocytosis, a mechanism by which pathogens and foreign particles are engulfed in order to be contained, killed, and processed. We investigated the phenotypic and genetic variation related to phagocytosis in two allopatric populations of the butterfly Pieris napi. Populations were found to differ in their hemocyte composition and overall phagocytic capability, driven by the increased phagocytic propensity of each cell type. Yet, genes annotated to phagocytosis showed no large genomic signal of divergence. However, a gene set enrichment analysis on significantly divergent genes identified loci involved in glutamine metabolism, which recently have been linked to immune cell differentiation in mammals. Together these results suggest that heritable variation in phagocytic capacity arises via a quantitative trait architecture with variation in genes affecting the activation and/or differentiation of phagocytic cells, suggesting them as potential candidate genes underlying these phenotypic differences.
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| 3. |
- Keehnen, Naomi L. P., et al.
(författare)
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Physiological Tradeoffs of Immune Response Differs by Infection Type in Pieris napi
- 2021
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the tradeoffs that result from successful infection responses is central to understanding how life histories evolve. Gaining such insights, however, can be challenging, as they may be pathogen specific and confounded with experimental design. Here, we investigated whether infection from gram positive or negative bacteria results in different physiological tradeoffs, and whether these infections impact life history later in life (post-diapause development), in the butterfly Pieris napi. During the first 24 h after infection (3, 6, 12, and 24 h), after removing effects due to injection, larvae infected with Micrococcus luteus showed a strong suppression of all non-immunity related processes while several types of immune responses were upregulated. In contrast, this tradeoff between homeostasis and immune response was much less pronounced in Escherichia coli infections. These differences were also visible long after infection, via weight loss and slower development, as well as an increased mortality at higher infection levels during later stages of development. Individuals infected with M. luteus, compared to E. coli, had a higher mortality rate, and a lower pupal weight, developmental rate and adult weight. Further, males exhibited a more negative impact of infection than females. Thus, immune responses come at a cost even when the initial infection has been overcome, and these costs are likely to affect later life history parameters with fitness consequences.
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| 4. |
- Keehnen, Naomi L. P., et al.
(författare)
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The consequences of surviving infection across the metamorphic boundary : tradeoff insights from RNAseq and life history measures
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The broad diversity of insect life has been shaped, in part, by pathogen pressure, yet the influence of injury and infection during critical periods of development is understudied. During development, insects undergo metamorphosis, wherein the organism experiences a dramatic shift in their overall morphology, and physiology. In temperate zones, metamorphosis is often directly followed by a developmental arrest called diapause, for which the insect needs to acquire enough energy reserves before the onset of winter. We investigated the long-term effects of injury and infection using two bacteria in the butterfly Pieris napi, revealing that the negative consequences of bacterial infection carry across the metamorphic boundary. Initial direct effects of infection were weight loss and slower development, as well as an increased mortality at higher infection levels. The detrimental effects were stronger in the gram-positive Micrococcus luteus compared to gram-negative Escherichia coli. Transcriptome-wide differences between the two bacteria were already observed in the gene expression profile of the first 24 hours after infection. Larvae infected with M. luteus showed a strong suppression of all non-immunity related processes, with several types of immune responses being activated. The impact of these transcriptomic changes, a tradeoff between homeostasis and immune response, were visible in the life history data, wherein individuals infected with M. luteus had the highest mortality rate, along with the lowest pupal weight, developmental rate and adult weight of all the treatments. Overall, we find that the cost of infection and wounding in the final larval instar carries over the metamorphic boundary, and is expected to negatively affect their lifetime fitness.
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| 5. |
- Kubrak, Olga I., et al.
(författare)
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Characterization of Reproductive Dormancy in Male Drosophila melanogaster
- 2016
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Insects are known to respond to seasonal and adverse environmental changes by entering dormancy, also known as diapause. In some insect species, including Drosophila melanogaster, dormancy occurs in the adult organism and postpones reproduction. This adult dormancy has been studied in female flies where it is characterized by arrested development of ovaries, altered nutrient stores, lowered metabolism, increased stress and immune resistance and drastically extended lifespan. Male dormancy, however, has not been investigated in D. melanogaster, and its physiology is poorly known in most insects. Here we show that unmated 3-6 h old male flies placed at low temperature (11 degrees C) and short photoperiod (10 Light:14 Dark) enter a state of dormancy with arrested spermatogenesis and development of testes and male accessory glands. Over 3 weeks of diapause we see a dynamic increase in stored carbohydrates and an initial increase and then a decrease in lipids. We also note an up-regulated expression of genes involved in metabolism, stress responses and innate immunity. Interestingly, we found that male flies that entered reproductive dormancy do not attempt to mate females kept under non-diapause conditions (25 degrees C, 1 2L:1 2D), and conversely non-diapausing males do not mate females in dormancy. In summary, our study shows that male D. melanogaster can enter reproductive dormancy. However, our data suggest that dormant male flies deplete stored nutrients faster than females, studied earlier, and that males take longer to recover reproductive capacity after reintroduction to non-diapause conditions.
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| 6. |
- Kucerova, Lucie, et al.
(författare)
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Slowed aging during reproductive dormancy is reflected in genome-wide transcriptome changes in Drosophila melanogaster
- 2016
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: In models extensively used in studies of aging and extended lifespan, such as C. elegans and Drosophila, adult senescence is regulated by gene networks that are likely to be similar to ones that underlie lifespan extension during dormancy. These include the evolutionarily conserved insulin/IGF, TOR and germ line-signaling pathways. Dormancy, also known as dauer stage in the larval worm or adult diapause in the fly, is triggered by adverse environmental conditions, and results in drastically extended lifespan with negligible senescence. It is furthermore characterized by increased stress resistance and somatic maintenance, developmental arrest and reallocated energy resources. In the fly Drosophila melanogaster adult reproductive diapause is additionally manifested in arrested ovary development, improved immune defense and altered metabolism. However, the molecular mechanisms behind this adaptive lifespan extension are not well understood. Results: A genome wide analysis of transcript changes in diapausing D. melanogaster revealed a differential regulation of more than 4600 genes. Gene ontology (GO) and KEGG pathway analysis reveal that many of these genes are part of signaling pathways that regulate metabolism, stress responses, detoxification, immunity, protein synthesis and processes during aging. More specifically, gene readouts and detailed mapping of the pathways indicate downregulation of insulin-IGF (IIS), target of rapamycin (TOR) and MAP kinase signaling, whereas Toll-dependent immune signaling, Jun-N-terminal kinase (JNK) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways are upregulated during diapause. Furthermore, we detected transcriptional regulation of a large number of genes specifically associated with aging and longevity. Conclusions: We find that many affected genes and signal pathways are shared between dormancy, aging and lifespan extension, including IIS, TOR, JAK/STAT and JNK. A substantial fraction of the genes affected by diapause have also been found to alter their expression in response to starvation and cold exposure in D. melanogaster, and the pathways overlap those reported in GO analysis of other invertebrates in dormancy or even hibernating mammals. Our study, thus, shows that D. melanogaster is a genetically tractable model for dormancy in other organisms and effects of dormancy on aging and lifespan.
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