The presentation of exogenous antigens on MHC class I molecules, known as cross-presentation, is essential for the initiation of CD8(+) T cell responses. In vivo, cross-presentation is mainly carried ...out by specific dendritic cell (DC) subsets through an adaptation of their endocytic and phagocytic pathways. Here, we summarize recent advances in our understanding of the intracellular mechanisms of cross-presentation and discuss its role in immunity and tolerance in the context of specialization between DC subsets. Finally, we review current strategies to use cross-presentation for immunotherapy.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Over the course of just a few years, shrimp farming has become a major aquaculture production system in coastal areas of several developing countries across the globe. However, farmers are facing a ...variety of risks related to disease, market, and climate, which influence risk management strategies and adoption of new technologies. This paper looks at three practices related to pond management: (1) water quality management to ensure a good environment for shrimp growth; (2) adequate feed input; and (3) disease control practices in order to mitigate the risk of disease outbreak in the pond. We investigated adoption of these three practices in smallholder shrimp farms in the Mekong Delta, by exploring how and whether membership into a producer's cluster influences access to knowledge and perception of risk in the adoption process. The results show that, after controlling for farm characteristics, farm clustering has a positive relationship with the adoption of water quality management, feed inputs, and disease control practices. Results also indicate that increasing interaction frequency with public sector and private sector's actors, as well as the perceived degree of market risk, positively influences the adoption of the three pond management practices under study. Mediation analyses show that being a member of a farmer cluster influences adoption of farming practices via two underlying processes: frequency of interaction with public and private sector's actors, and perception of market risk, both of which ultimately promote the adoption of practices. We conclude that clustering is a promising avenue for fostering interactions between farmers and key supporting actors in aquaculture, and impacts both the formation of specific aqua-related risk perceptions and subsequent practice adoption. As such, clusters – by fostering linkages and facilitating interactions between different knowledge sources – can promote adoption of practices toward sustainable intensification. However, to more effectively deploy a cluster approach a key policy and practice implication is to take into consideration local idiosyncrasies defined by their social interactions, risk perception and spatial dimensions in order to better facilitate local linkages between farms (horizontal coordination) and a better integration with the value chain (vertical coordination).
•Clustering enhances interactions of farmers with value chain's actors.•Farmer clusters have a positive effect on adoption of aquaculture practices.•Increased interactions with non-farmer actors promote adoption.•Market risk perception is key in adoption of aquaculture practices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Shrimp farming is considered a “risky business” and often compared to gambling for farmers. It is associated with a diverse range of risks and uncertainties, including volatile markets, climate ...variability, and production risks. In order to mitigate the effects of unpredictability farmers may decide on a particular stocking density and adopt different risk management strategies. Aquaculture research has paid little attention to the influence played by the evaluation and selection of different farming practices, risk perceptions associated with shrimp farming, and the farmers' confidence in their own ability to mitigate risk. The objective of this paper is to analyze the case of shrimp farming in Vietnam's Mekong Delta, where different types of shrimp farms (extensive, semi-intensive and intensive) co-exist within the same landscape, to identify the underlying factors driving stocking behavior and the adoption of different risk management strategies.
A survey of 250 farms showed that perceptions toward different stocking behaviors (from extensive to intensive) varied according to the species raised (Penaeus monodon or P. vannamei) and the type of farm. At low density, farmers consider P. monodon as more productive and easier to adopt than P. vannamei. Adoption of intensive farming practices for both species is negatively associated with risk of disease emergence. However, expected productivity is not a predictor of adoption of intensive shrimp farming practices. Mediation analysis indicates that risk management strategies are significantly influenced by perceived market risk. The perception of this type of risk is a key predictor of risk management strategies. The farmers' lack of access to efficient market risk mitigation measures reflects inadequate or missing regulations or lack of specific value chain organization to mitigate this type of risk. Using a behavioral approach provides new insight on how farmers manage their farms, address risk and implement risk management strategies. It showed that farmers, unlike actual gamblers, adopt diverse management strategies after carefully evaluating species and stocking density as well as critically assessing different sources of risk.
•Evaluation of stocking practices and species varies according to farming types.•Risk perception and confidence in mitigating risk vary according to farming types.•Perception of market risk is key in choosing risk management strategies.•Behavioral approaches explain what drives the farmers' management choices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Aquaculture has experienced spectacular growth in the past decades, during which continuous innovation has played a significant role, but it faces increasing criticism regarding its ecological and ...social sustainability practices and the resulting challenges for future innovation processes. However, in the aquaculture literature, there is limited systematic knowledge of how innovation has been approached in terms of how the focus and the scope of aquaculture innovation processes are understood and managed. The objective of this paper is therefore to analyse the different approaches to innovation used in aquaculture development. We conducted a systematic review of the aquaculture literature, using an analytical lens derived from three main bodies of literature on approaches to conceptualize and manage innovation: Technology-driven, Systemic, and Business and Managerial approaches to innovation. One hundred publications were selected from the aquaculture literature covering the topic of aquaculture innovation. Analysis identified the Transfer of Technology approach as still the predominant approach to aquaculture innovation; and, even with the integration of elements of Systemic approaches, most studies remain focused on the farm level and are technology driven. Multi-dimensional studies, integrating technical, biophysical, political, and institutional dimensions of innovation in aquaculture were found, but studies analysing interactions between levels remain scarce, have a strong emphasis on the institutional dimension, and lack focus on the management of the innovation process. Studies with cross-fertilizations between different approaches to aquaculture innovation are limited but address specific research questions regarding the extent to which specific target groups are included in interventions and the need to incorporate diverse dimensions in analysing innovation processes. Our analysis suggests that aquaculture research and technology design that feeds into aquaculture innovation could benefit from innovation management approaches that integrate constant feedback from users, especially when specific groups are being targeted for better inclusiveness, and thus could better foster multi-directional interactions between multiple actors connected to aquaculture systems. This would help to elevate the analysis from just the farm and improve the integration of institutional, political, economic, and socio-cultural dimensions for better management of the innovation process. The study of aquaculture innovation needs to take into consideration the important role of private sector actors and make better use of systemic approaches to further elucidate the multi-dimensional and multi-level interplays in complex aquaculture systems. Ultimately, interdisciplinary research on aquaculture innovation could deliver significant insights supporting the development of a resilient and sustainable aquaculture sector.
Using an analytical lens derived from the literature on innovation approaches, this study systematically analyses approaches to innovation used in aquaculture development. We identify the main trends and existing gaps in aquaculture innovation research and then discuss the potential complementarities between different approaches to innovation in order to better understand and support innovation in the aquaculture sector.
•First systematic review of how the aquaculture literature has approached innovation.•The Transfer of Technology approach with a farm-level focus is still the predominant approach to aquaculture innovation.•Studies with cross-fertilizations between different approaches to aquaculture innovation are limited.•A new framework for innovation in aquaculture proposes cross-fertilization between approaches to address complex problems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Most T lymphocytes, including regulatory T cells (Treg cells), differentiate in the thymus. The age-dependent involution of this organ leads to decreasing production of T cells. Here we found that ...the output of new Treg cells from the thymus decreased substantially more than that of conventional T cells. Peripheral mouse and human Treg cells recirculated back to the thymus, where they constituted a large proportion of the pool of Treg cells and displayed an activated and differentiated phenotype. In the thymus, the recirculating cells exerted their regulatory function by inhibiting interleukin 2 (IL-2)-dependent de novo differentiation of Treg cells. Thus, Treg cell development is controlled by a negative feedback loop in which mature progeny cells return to the thymus and restrain development of precursors of Treg cells.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Upon activation, naive CD4+ T cells differentiate into distinct T cell subsets via processes reliant on epigenetically regulated, lineage-specific developmental programs. Here, we examined the ...function of the histone methyltransferase SETDB1 in T helper (Th) cell differentiation. Setdb1−/− naive CD4+ T cells exhibited exacerbated Th1 priming, and when exposed to a Th1-instructive signal, Setdb1−/− Th2 cells crossed lineage boundaries and acquired a Th1 phenotype. SETDB1 did not directly control Th1 gene promoter activity but relied instead on deposition of the repressive H3K9me3 mark at a restricted and cell-type-specific set of endogenous retroviruses (ERVs) located in the vicinity of genes involved in immune processes. Refined bioinformatic analyses suggest that these retrotransposons regulate Th1 gene cis-regulatory elements or act as Th1 gene enhancers. Thus, H3K9me3 deposition by SETDB1 ensures Th cell lineage integrity by repressing a repertoire of ERVs that have been exapted into cis-regulatory modules to shape and control the Th1 gene network.
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•Setdb1−/− naive CD4+ T cells have exacerbated Th1 priming and unstable Th2 commitment•In Th2 cells, SETDB1 deposits the repressive H3K9me3 mark at a limited set of ERVs•In Th2 cells, the ERVs marked by H3K9me3 behave as Th1 gene cis-regulatory modules•SETDB1 ensures Th2 cell stability by repressing ERVs that control the Th1 gene network
Adoue et al. find that the histone methyltransferase SETDB1 ensures T helper cell lineage integrity not by directly controlling genes associated with T helper cell differentiation but rather by repressing a restricted set of endogenous retroviruses that have been co-opted for the regulation of immune genes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The shrimp sector has been one of the fastest growing agri-food systems in the last decades, but its growth has entailed negative social and environmental impacts. Sustainable intensification will ...require innovation in multiple elements of the shrimp production system and its value chain. We use the case of the shrimp sector in the Mekong Delta in Vietnam to explore the constraints in the transition to sustainable intensification in shrimp farming, using an analytical framework based on innovation systems thinking, i.e., an aquaculture innovation systems framework. Using this framework, we conduct a systemic diagnostic of blocking mechanisms, interrelated sets of constraints within the aquaculture sector that hinder a transition toward sustainable intensification. Our findings show that the major constraints are institutional, with limited enforcement of the regulatory framework for input quality control, disease control, and wastewater management, and a lack of coordination between government bodies to design and enforce this framework. At farm level, limited access to capital favors pond mismanagement and the use of low-quality inputs. The absence of multi-stakeholder initiatives to foster dialog between actors in the value chain constrains the response to new regulations dictated by international market demand. Because of shrimp farming’s connectivity with the wider ecosystem, sustainable intensification in shrimp farming will require collective management of water resources at the landscape level for disease and water pollution control. Ecological principles for pond management need to be promoted to farmers in order to reduce farmers’ inefficient practices and build their capacity to understand new techniques and inputs available in the Vietnamese market. Our paper demonstrates for the utility of a multi-level, multi-dimension, and multi-stakeholder aquaculture innovation systems approach to analyze and address these blocking mechanisms in the transition to sustainable intensification in shrimp farming and aquaculture more broadly.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A common avenue to enable adoption of technologies and practices by small-scale producers is by means of farmer clusters. These are achieved by building networks and partnerships between farmers and ...other actors within the supply chain. This paper examines the role that farmer clusters play in the adoption of practices and technologies by shrimp farmers in Vietnam. Understanding the decisions that lead to adoption is important because these have a key impact on sustainable land use in aquaculture. We report on two complementary studies that test the role of farmer clusters in accessing different sources of knowledge and the trust associated with each of the knowledge sources. First, a survey (N = 193) tested the relationship between cluster membership and adoption, and showed that shrimp farmers who are members of farmer clusters are more likely to adopt three types of pond management practices (i.e. water quality management, feed input, and disease control practices). Furthermore, frequency of interaction with, and trust related to, key stakeholder actors could partly explain this relationship. Second, focus group discussions further zoomed into the dynamics that underlie the adoption of technologies and practices by cluster farmers and non-cluster farmers, respectively. We found that input retailers, buyers and hatcheries were only valued for their input on specific products and issues, but not trusted, as the information always needed being verified through testing by, amongst others, neighbors. Consequently, trust relations with these actors can be described as strongly calculative. Farmer clusters increase trust and tighten relationships between members. As a result, members trust each other when verifying information or sharing knowledge acquired from less trusted sources. On the basis of these results, we argue that reliance on existing farmer networks (i.e. clusters) is a viable tool to improve adoption of sustainable technologies and achieve land use planning objectives. Further implications for research and policy are discussed.
•Membership in a farmer cluster facilitates adoption of practices and technologies.•Increased frequency of interaction improves how much a source is trusted.•Trust is specific to the type of source of knowledge and information.•Farmer clusters can be a tool to achieve sustainable aquaculture practices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The mouse CD8alpha+ DC subset excels at cross-presentation of antigen, which can elicit robust CTL responses. A receptor allowing specific antigen targeting to this subset and its equivalent in ...humans would therefore be useful for the induction of antitumor CTLs. Here, we have characterized a C-type lectin of the NK cell receptor group that we named DC, NK lectin group receptor-1 (DNGR-1). DNGR-1 was found to be expressed in mice at high levels by CD8+ DCs and at low levels by plasmacytoid DCs but not by other hematopoietic cells. Human DNGR-1 was also restricted in expression to a small subset of blood DCs that bear similarities to mouse CD8alpha+ DCs. The selective expression pattern and observed endocytic activity of DNGR-1 suggested that it could be used for antigen targeting to DCs. Consistent with this notion, antigen epitopes covalently coupled to an antibody specific for mouse DNGR-1 were selectively cross-presented by CD8alpha+ DCs in vivo and, when given with adjuvants, induced potent CTL responses. When the antigens corresponded to tumor-expressed peptides, treatment with the antibody conjugate and adjuvant could prevent development or mediate eradication of B16 melanoma lung pseudometastases. We conclude that DNGR-1 is a novel, highly specific marker of mouse and human DC subsets that can be exploited for CTL cross-priming and tumor therapy.
Pathogen invasion induces a rapid inflammatory response initiated through the recognition of pathogen-derived molecules by pattern recognition receptors (PRRs) expressed on both immune and non-immune ...cells. The initial wave of pro-inflammatory cytokines and chemokines limits pathogen spread and recruits and activates immune cells to eradicate the invaders. Dendritic cells (DCs) are responsible for initiating a subsequent phase of immunity, dominated by the action of pathogen-specific T and B cells. As for the early pro-inflammatory response, DC activation is triggered by PRR signals. These signals convert resting DCs into potent antigen-presenting cells capable of promoting the expansion and effector differentiation of naive pathogen-specific T cells. However, it has been argued that signals from PRRs are not a prerequisite for DC activation and that pro-inflammatory cytokines have the same effect. Although this may appear like an efficient way to expand the number of DCs that initiate adaptive immunity, evidence is accumulating that DCs activated indirectly by inflammatory cytokines are unable to induce functional T-cell responses. Here, we review the differences between PRR-triggered and cytokine-induced DC activation and speculate on a potential role for DCs activated by inflammatory signals in tolerance induction rather than immunity.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
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