| 1. |
- Anderl, Ines, et al.
(författare)
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Transdifferentiation and Proliferation in Two Distinct Hemocyte Lineages in Drosophila melanogaster Larvae after Wasp Infection
- 2016
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Ingår i: PLoS Pathogens. - : Public library science. - 1553-7366 .- 1553-7374. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Cellular immune responses require the generation and recruitment of diverse blood cell types that recognize and kill pathogens. In Drosophila melanogaster larvae, immune-inducible lamellocytes participate in recognizing and killing parasitoid wasp eggs. However, the sequence of events required for lamellocyte generation remains controversial. To study the cellular immune system, we developed a flow cytometry approach using in vivo reporters for lamellocytes as well as for plasmatocytes, the main hemocyte type in healthy larvae. We found that two different blood cell lineages, the plasmatocyte and lamellocyte lineages, contribute to the generation of lamellocytes in a demand-adapted hematopoietic process. Plasmatocytes transdifferentiate into lamellocyte-like cells in situ directly on the wasp egg. In parallel, a novel population of infection-induced cells, which we named lamelloblasts, appears in the circulation. Lamelloblasts proliferate vigorously and develop into the major class of circulating lamellocytes. Our data indicate that lamellocyte differentiation upon wasp parasitism is a plastic and dynamic process. Flow cytometry with in vivo hemocyte reporters can be used to study this phenomenon in detail.
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| 2. |
- Nousiainen, Marko, et al.
(författare)
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Are Alternative Food Systems Socially Sustainable? : A Case Study from Finland
- 2009
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Ingår i: Journal of Sustainable Agriculture. - : Informa UK Limited. - 1044-0046 .- 1540-7578. ; 33:5, s. 566-594
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Tidskriftsartikel (refereegranskat)abstract
- This paper explores the importance of alternative food systems in delivering social sustainability to local communities. The perceptions of local and organic food systems actors regarding equity (or fairness) between the actors and viability of the local communities are examined to analyze social sustainability in Juva, Finland. The findings lend conditional support to the positive relationship between localized food systems and actors within these systems feeling empowered and influential, while also supporting other research emphasizing the limitations of farmer influence on vertical distributional channels, irrespective of production methods (i.e., organic or conventional).
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| 3. |
- Räsänen, Matti, et al.
(författare)
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Carbon dioxide and methane fluxes from mounds of African fungus-growing termites
- 2023
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Ingår i: Biogeosciences. - 1726-4170. ; 20:19, s. 4029-4042
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Tidskriftsartikel (refereegranskat)abstract
- Termites play an essential role in decomposing dead plant material in tropical ecosystems and are thus major sources of gaseous C emissions in many environments. In African savannas, fungus-growing termites are among the ecologically most influential termite species. We studied the gas exchange from mounds of two closely related fungus-growing species (Macrotermes subhyalinus and M. michaelseni, respectively) in two habitats representing different vegetation types (grassland, bushland) together with soil fluxes around the mounds. The fluxes from active termite mounds varied from 120 to 2100 mg CO2-C m-2h-1 for carbon dioxide (CO2) and from 0.06 to 3.7 mg CH4-C m-2 h-1 for methane (CH4) fluxes. Mound CO2 fluxes varied seasonally with a 64 % decrease and 41 % increase in the fluxes from the dry to wet season at the grassland and bushland sites, respectively. During the wet season, the CO2 fluxes were significantly correlated with termite mound volume. The diurnal measurements from two M. michaelseni mounds suggest that the gas fluxes peak during the daytime, possibly reflecting changes in mound internal air circulation. Soil fluxes of both CO2 and CH4 were enhanced at up to 2 m distance from the mounds compared to the local soil respiration, indicating that, in addition to mound ventilation structures, a small proportion of the metabolic gases produced also leave the nest via surrounding soils.
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| 4. |
- Vanha-aho, Leena-Maija, et al.
(författare)
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Edin expression in the fat body is required in the defense against parasitic wasps in Drosophila melanogaster
- 2015
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Ingår i: PLoS Pathogens. - : Public library science. - 1553-7366 .- 1553-7374. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- The cellular immune response against parasitoid wasps in Drosophila involves the activation, mobilization, proliferation and differentiation of different blood cell types. Here, we have assessed the role of Edin (elevated during infection) in the immune response against the parasitoid wasp Leptopilina boulardi in Drosophila melanogaster larvae. The expression of edin was induced within hours after a wasp infection in larval fat bodies. Using tissue-specific RNAi, we show that Edin is an important determinant of the encapsulation response. Although edin expression in the fat body was required for the larvae to mount a normal encapsulation response, it was dispensable in hemocytes. Edin expression in the fat body was not required for lamellocyte differentiation, but it was needed for the increase in plasmatocyte numbers and for the release of sessile hemocytes into the hemolymph. We conclude that edin expression in the fat body affects the outcome of a wasp infection by regulating the increase of plasmatocyte numbers and the mobilization of sessile hemocytes in Drosophila larvae.
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| 5. |
- Vesala, Laura, et al.
(författare)
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Mitochondrial perturbation in immune cells enhances cell-mediated innate immunity in Drosophila
- 2024
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Ingår i: BMC Biology. - : BioMed Central (BMC). - 1741-7007. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mitochondria participate in various cellular processes including energy metabolism, apoptosis, autophagy, production of reactive oxygen species, stress responses, inflammation and immunity. However, the role of mitochondrial metabolism in immune cells and tissues shaping the innate immune responses are not yet fully understood. We investigated the effects of tissue-specific mitochondrial perturbation on the immune responses at the organismal level. Genes for oxidative phosphorylation (OXPHOS) complexes cI-cV were knocked down in the fruit fly Drosophila melanogaster, targeting the two main immune tissues, the fat body and the immune cells (hemocytes).Results: While OXPHOS perturbation in the fat body was detrimental, hemocyte-specific perturbation led to an enhanced immunocompetence. This was accompanied by the formation of melanized hemocyte aggregates (melanotic nodules), a sign of activation of cell-mediated innate immunity. Furthermore, the hemocyte-specific OXPHOS perturbation induced immune activation of hemocytes, resulting in an infection-like hemocyte profile and an enhanced immune response against parasitoid wasp infection. In addition, OXPHOS perturbation in hemocytes resulted in mitochondrial membrane depolarization and upregulation of genes associated with the mitochondrial unfolded protein response.Conclusions: Overall, we show that while the effects of mitochondrial perturbation on immune responses are highly tissue-specific, mild mitochondrial dysfunction can be beneficial in immune-challenged individuals and contributes to variation in infection outcomes among individuals.
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