Nursery production without peat : an insight into peat-free nurseries in the UK

Torvmarker täcker ~3% av världens landyta och har sedan senaste istiden fungerat som en viktig kolsänka, som tar upp koldioxid (CO2) ur atmosfären. Ungefär 10% av torvmarkerna på jorden har dränerats, huvudsakligen för skogs- och lantbruk, samt till viss del för torvbruk. Genom utdikning förlorar torvmarker sin funktion som kolsänka, och i stället ger den utdikade arealen upphov till ett utsläpp av 2 miljarder ton CO2 per år, som motsvarar ~5% av det mänsklig orsakade utsläpp av CO2. Eftersom återvätning av torvmarker kan vända denna process, har många länder satt i gång miljöprogram i syfte att skydda och återställer torvmarker. I Storbritannien har den politiska diskussionen kring torv lett till att användningen av odlingstorv ska fasas ut inom hela trädgårdsbranschen fram till 2030. Även om omsättningen av detta mål är frivilligt, finns det ett flertal plantskolor i Storbritannien som redan idag producerar sina containerodlade växter helt utan torv. Inom ramen för detta arbete kontaktades dessa plantskolor med en enkätundersökning i syfte att ta del av deras erfarenheter med torvfria odlingssystem. Främsta målen med detta var att ta reda på vilka odlingssubstrat dessa torvfria plantskolor använder i stället och att identifiera vilka fördelar och utmaningar som uppstår vid torvfri plantskoleproduktion. Det visade sig att kokosfiber, barkmull, träfiber, grönkompost och komposterad ull är de substratkomponenter som används mest i torvfria odlingssubstrat för containerodling i Storbritannien. Anpassningen av odlingssystemen till torvfria odlingssubstrat baserade på dessa komponenter upplevs av majoriteten som hanterbart. Ur resultaten framgick dock därutom att optimeringen av växtnäringsförsörjningen och bevattningsrutinerna kan upplevas som utmanande och således rekommenderas att dessa arbetsmoment bör kontrolleras noggrant. Dessutom upplevs den delvis begränsade tillgängligheten och varierande kvaliteten av torvfria odlingssubstrat som problematisk. Som fördelaktigt upplever odlarna fram för allt att märkningen som en ”torvfri plantskola” är bra för marknadsföringen och kan således utnyttjas för att attrahera både, privat- och företagskunder, som vill handla hållbart producerade växter. Sammanlagt visar resultaten av detta arbete att det är fullt möjligt att producera ett brett sortiment av olika växtslag helt utan torv, såväl i liten som stor skala, och att en torvfri plantskola kan vara en lönsam affärsmodell.Peatlands cover ~3% of the earth´s land surface and have since the last ice age functioned as an important carbon sink, taking up carbon dioxide (CO2) from the atmosphere. About 10% of the global peatlands have been drained, mainly for forestry and agriculture, and to some extent for peat extraction. Drained peatlands not only lose their function as carbon sinks, but instead give rise to an emission of almost 2 billion tonnes of CO2 per year, which corresponds to ~5% of the human-caused CO2 emissions. Because rewetting of peatlands can reverse this process, many countries have launched environmental programs aimed at protecting and restoring peatlands. In the United Kingdom (UK), the political discussion about peat has led to the decision that the use of peat has to be phased out within the entire horticultural industry by 2030. Although the implementation of this goal is voluntary, there are several nurseries in the UK that already produce their container-grown plants completely without peat. As part of this study, these nurseries were contacted with a survey to take part in their experiences with peat-free cultivation systems. The main objectives of this were to investigate which growing media these peat-free nurseries use to replace peat and to identify the benefits and challenges that arise in peat-free nursery production. The results show that coir, composted bark, wood fibre, green compost and composted wool are the substrate components most used in peat-free growing media for container nursery production in the UK. The adaptation of the cultivation systems to peat-free growing media based on these components is perceived by the majority as manageable. However, the results also showed that the optimisation of plant nutrition and irrigation routines can be perceived as challenging and thus it is recommended that these aspects should be controlled carefully. In addition, the partly limited availability and varying quality of peat-free growing media is perceived as problematic. As main advantage the nurseries experience that the label “peat-free” is good for marketing and can thus be used to attract both, private and corporate customers, who want to buy sustainably produced plants. Overall, the results of this study show that it is possible to produce a wide range of different plant species completely without peat, both on small and large scale, and that a peat-free nursery can be a profitable business model

Prevention of colitis-associated cancer by selective targeting of immunoproteasome subunit LMP7

Chronic inflammation is a well-known risk factor in development of intestinal tumorigenesis, although the exact mechanisms underlying development of colitis-associated cancer (CAC) still remain obscure. The activity and function of immunoproteasome has been extensively analyzed in the context of inflammation and infectious diseases. Here, we show that the proteasomal immunosubunit LMP7 plays an essential role in development of CAC. Mice devoid of LMP7 were resistant to chronic inflammation and formation of neoplasia, and developed virtually no tumors after AOM/DSS treatment. Our data reveal that LMP7 deficiency resulted in reduced expression of pro-tumorigenic chemokines CXCL1, CXCL2 and CXCL3 as well as adhesion molecule VCAM-1. As a consequence, an impaired recruitment and activity of tumor-infiltrating leukocytes resulting in decreased secretion of cytokines IL-6 and TNF-α was observed. Further, the deletion or pharmacological inhibition of LMP7 and consequent blockade of NF-κB abrogated the production of IL-17A, which possesses a strong carcinogenic activity in the gut. Moreover, in vivo administration of the selective LMP7 inhibitor ONX-0914 led to a marked reduction of tumor numbers in wild-type (WT) mice. Collectively, we identified the immunoproteasome as a crucial mediator of inflammation-driven neoplasia highlighting a novel potential therapeutic approach to limit colonic tumorigenesis

Diversity and functions of intestinal mononuclear phagocytes

The intestinal lamina propria (LP) contains a diverse array of mononuclear phagocyte (MNP) subsets, including conventional dendritic cells (cDC), monocytes and tissue-resident macrophages (mφ) that collectively play an essential role in mucosal homeostasis, infection and inflammation. In the current review we discuss the function of intestinal cDC and monocyte-derived MNP, highlighting how these subsets play several non-redundant roles in the regulation of intestinal immune responses. While much remains to be learnt, recent findings also underline how the various populations of MNP adapt to deal with the challenges specific to their environment. Understanding these processes should help target individual subsets for 'fine tuning' immunological responses within the intestine, a process that may be of relevance both for the treatment of inflammatory bowel disease (IBD) and for optimized vaccine design

The Proteasome System in Infection: Impact of β5 and LMP7 on Composition, Maturation and Quantity of Active Proteasome Complexes

Proteasomes are the major enzyme complexes for non-lysosomal protein degradation in eukaryotic cells. Mammals express two sets of catalytic subunits: the constitutive subunits β1, β2 and β5 and the immunosubunits LMP2 (β1i), MECL-1 (β2i) and LMP7 (β5i). The LMP7-propeptide (proLMP7) is required for optimal maturation of LMP2/MECL-1-containing precursors to mature immunoproteasomes, but can also mediate efficient integration into mixed proteasomes containing β1 and β2. In contrast, the β5-propeptide (proβ5) has been suggested to promote preferential integration into β1/β2-containing precursors, consequently favouring the formation of constitutive proteasomes. Here, we show that proβ5 predominantly promotes integration into LMP2/MECL-1-containing precursors in IFNγ-stimulated, LMP7-deficient cells and infected LMP7-deficient mice. This demonstrates that proβ5 does not direct preferential integration into β1/β2-containing precursors, but instead promotes the formation of mixed LMP2/MECL-1/β5 proteasomes under inflammatory conditions. Moreover, the propeptides substantially differ in their capacity to promote proteasome maturation, with proLMP7 showing a significantly higher chaperone activity as compared to proβ5. Increased efficiency of proteasome maturation mediated by proLMP7 is required for optimal MHC class I cell surface expression and is equally important as the catalytic activity of immunoproteasomes. Intriguingly, induction of LMP7 by infection not only results in rapid exchange of constitutive by immunosubunits, as previously suggested, but also increases the total proteasome abundance within the infected tissue. Hence our data identify a novel LMP7-dependend mechanism to enhance the activity of the proteasome system in infection, which is based on the high chaperone activity of proLMP7 and relies on accelerated maturation of active proteasome complexes

Virulence of Group A Streptococci Is Enhanced by Human Complement Inhibitors

Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement and consequent phagocytosis. Several strains of GAS bind to human-specific complement inhibitors, C4b-binding protein (C4BP) and/or Factor H (FH), to curtail complement C3 (a critical opsonin) deposition. This results in diminished activation of phagocytes and clearance of GAS that may lead to the host being unable to limit the infection. Herein we describe the course of GAS infection in three human complement inhibitor transgenic (tg) mouse models that examined each inhibitor (human C4BP or FH) alone, or the two inhibitors together (C4BPxFH or 'double' tg). GAS infection with strains that bound C4BP and FH resulted in enhanced mortality in each of the three transgenic mouse models compared to infection in wild type mice. In addition, GAS manifested increased virulence in C4BPxFH mice: higher organism burdens and greater elevations of pro-inflammatory cytokines and they died earlier than single transgenic or wt controls. The effects of hu-C4BP and hu-FH were specific for GAS strains that bound these inhibitors because strains that did not bind the inhibitors showed reduced virulence in the 'double' tg mice compared to strains that did bind; mortality was also similar in wild-type and C4BPxFH mice infected by non-binding GAS. Our findings emphasize the importance of binding of complement inhibitors to GAS that results in impaired opsonization and phagocytic killing, which translates to enhanced virulence in a humanized whole animal model. This novel hu-C4BPxFH tg model may prove invaluable in studies of GAS pathogenesis and for developing vaccines and therapeutics that rely on human complement activation for efficacy

The impact of [beta] 5i-deficiency on structure and function of 20S proteasomes in Listeria monocytogenes infection

Das Proteasomsystem ist die Hauptquelle von Peptiden für die MHC Klasse I Antigen-Präsentation. In Vertebraten kann dieses durch die Expression verschiedener Subtypen des 20S Proteasoms moduliert werden. Die häufigsten Subtypen sind konstitutive Proteasomen (c20S) mit den katalytischen Untereinheiten beta1, beta2 und beta5 und Immunoproteasomen (i20S) mit den Immunountereinheiten beta1i, beta2i und beta5i. Die Expression von i20S optimiert in der Regel die MHC Klasse I Antigen-Präsentation, indem die Bildung von Peptiden mit hoher Affinität zu MHC I Molekülen verstärkt wird. Die Bildung von i20S wird momentan durch ein Modell der kooperativen Assemblierung erklärt, das auf der präferentiellen Interaktion zwischen den Immunountereinheiten beruht. In dieser Arbeit wurde die Assemblierung von 20S Proteasomen in beta5i defizienten Mäusen nach Infektion mit Listeria monocytogenes analysiert. In diesem Modell konnte keine präferentielle Interaktion zwischen den Untereinheiten festgestellt werden. Stattdessen zeigen die Ergebnisse, daß die Integration von konstitutiven oder Immunountereinheiten durch direkte Kompetition reguliert wird. Des Weiteren wurde während der Infektion eine beta5i-abhängige Zunahme der zellulären Proteasommenge festgestellt und somit ein neuer Mechanismus zur Regulation des zellulären Proteasomgehaltes entdeckt. Funktionell führt die beta5i-Defizienz zu einer verringerten MHC I Expression auf antigenpräsentierenden Zellen und zu einer verminderten Prozessierung des bakteriellen Antigens LLO296-304. Bei der Analyse der LLO296-304 spezifischen CD8 T Zell Antwort konnte jedoch kein Unterschied zwischen Wildtyp- und beta5i defizienten Mäusen festgestellt werden .Die Kontrolle der Infektion in den beta5i defizienten Mäusen ist jedoch in der Leber verzögert. Dies deutet darauf hin, dass die Erkennung und Elimination infizierter Zellen durch cytotoxische CD8 T Zellen auf Grund der geringeren MHC Klasse I Präsentation bakterieller Antigene behindert wird.The proteasome-system is the main source of peptides for MHC class I antigen presentation. In vertebrates this system can be modulated by the expression of different subtypes of the 20S proteasome. The most common subtypes are constitutive proteasomes (c20S) with the catalytic subunits beta1, beta2 and beta5 and immunoproteasomes (i20S) with the immunosubunits beta1i, beta2i and beta5i. Expression of i20S generally optimizes MHC class I antigen presentation by increasing the generation of peptides with high affinity to MHC class I molecules. Currently, the formation of i20S is explained by a model of cooperative proteasome assembly, which is based on preferential interactions among the immunosubunits. Here, the assembly of 20S proteasomes was analysed in beta5i deficient mice during an ongoing infection with Listeria monocytogenes. In this model, no preferential interactions among constitutive subunits or immunosubunits could be determined. Instead, the results show that the integration of constitutive subunits or immunosubunits is regulated by direct competition. Further, a beta5i-dependent increase in cellular proteasome quantity was observed following infection. This reveals a novel mechanism for the regulation of cellular proteasome quantity, which is based on the differential expression of beta5i. Functionally, the deficiency in beta5i results in a reduced MHC class I cell surface expression on professional antigen presenting cells and a drastically diminished processing of the bacterial antigen LLO296-304. However, the analyses of LLO296-304 specific CD8 T cells did not reveal differences in the frequencies of these T cells between wild-type and beta5i deficient mice. Still, the control of infection in the liver of beta5i deficient mice was delayed. This phenotype suggests that the recognition and elimination of infected target cells by cytotoxic CD8 T cells is constrained due to the lowered MHC class I presentation of bacterial antigens