Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Symposium review : Future of housing for dairy cattle
    Galama, P.J. ; Ouweltjes, W. ; Endres, M.I. ; Sprecher, J.R. ; Leso, L. ; Kuipers, A. ; Klopčič, M. - \ 2020
    Journal of Dairy Science 103 (2020)6. - ISSN 0022-0302 - p. 5759 - 5772.
    dairy cattle - environment - housing - innovation - welfare

    The objective of this review was to describe recent changes and expected developments in housing systems for dairy cows. These new developments should create an appropriate production environment for modern high-producing dairy cows and stimulate dairy farming-related developments in management, agro-technology, and equipment. Increased labor efficiency has been an important driver of the change from tie-stall barns to cubicle barns (also known as freestall barns). In future housing systems, the natural behavior of cows, climate control, emissions of ammonia and greenhouse gases, reuse of waste, manure quality, the aesthetics of buildings in the landscape, and capital efficiency are becoming increasingly important elements. To address future requirements, new concepts beyond cubicle barns must be developed. Freewalk housing systems; that is, loose housing systems without cubicles, would meet some of these future demands. These systems operate with composting bedding material or artificial permeable floors as lying and walking areas. However, these barns are still in development. Combinations of cubicle and freewalk housing systems, together with other techniques being developed, might become a major future housing system. Other techniques and systems that are being explored according to sustainability criteria include the multi-climate shed, the CowToilet (Hanskamp AgroTech, Doetinchem, the Netherlands) to separate feces and urine, and multifunctional buildings. These buildings and techniques can be part of land-based or, less commonly, city-based farming systems, such as floating farms.

    Invited review: Compost-bedded pack barns for dairy cows
    Leso, L. ; Barbari, M. ; Lopes, M.A. ; Damasceno, F.A. ; Galama, P. ; Taraba, J.L. ; Kuipers, A. - \ 2020
    Journal of Dairy Science 103 (2020)2. - ISSN 0022-0302 - p. 1072 - 1099.
    animal welfare - compost-bedded pack barn - dairy cow - housing system

    Compost-bedded pack barns (CBP) are receiving increasing attention as a housing system for dairy cows that has potential to improve animal welfare. This article reviews current scientific knowledge about CBP with the aim of providing a comprehensive tool for producers and researchers using this housing system. In CBP, cows are provided with an open bedded pack area rather than the individual stalls and concrete alleys found in freestall systems. The bedded pack, a mixture of organic bedding and cattle excreta, is cultivated frequently (1–3 times per day) to incorporate fresh manure and air into the pack, thus promoting an aerobic composting process. To function well, CBP generally require a large area per cow. Optimal animal densities over the bedded area range from 7.4 to more than 15 m2/cow depending on several factors, including climate, bedding, pack management, and cow characteristics. Studies have indicated that CBP, compared with conventional systems such as freestall barns, have the potential to improve the welfare of dairy cows. In particular, the main reported benefits include improved comfort during resting, better foot and leg health, and more natural animal behavior. Research has also indicated that adequate udder health can be achieved in CBP. However, because the bedded pack has been shown to contain high bacterial concentrations, proper management is essential to maintain adequate cow cleanliness and reduce the risk of mastitis. Controlling pack moisture is consistently indicated as the most important issue with CBP. Especially under cold and humid weather conditions, large amounts of bedding may be necessary to keep the pack adequately dry and comfortable for the cows. Nevertheless, the improvements in cow health may offset the higher costs of bedding.

    Improving the electrochemical production of hydrogen peroxide
    Bisselink, R.J.M. ; Zijlstra, Martin ; Goetheer, E. ; Kuipers, N.J.M. - \ 2019
    - 1 p.
    A single day of high-fat diet feeding induces lipid accumulation and insulin resistance in brown adipose tissue in mice
    Kuipers, Eline N. ; Held, Ntsiki M. ; Het Panhuis, Wietse In; Modder, Melanie ; Ruppert, Philip M.M. ; Kersten, Sander ; Kooijman, Sander ; Guigas, Bruno ; Houtkooper, Riekelt H. ; Rensen, Patrick C.N. ; Boon, Mariëtte R. - \ 2019
    American Journal of Physiology. Endocrinology and Metabolism 317 (2019)5. - ISSN 0193-1849 - p. E820 - E830.
    brown adipose tissue - high-fat diet - lipid accumulation - macrophage - mitochondrial dynamics

    Brown adipose tissue (BAT) catabolizes glucose and fatty acids to produce heat and thereby contributes to energy expenditure. Long-term high-fat diet (HFD) feeding results in so-called 'whitening' of BAT characterized by increased lipid deposition, mitochondrial dysfunction, and reduced fat oxidation. The aim of the current study was to unravel the rate and related mechanisms by which HFD induces BAT whitening and insulin resistance. Wild-type mice were fed a HFD for 0, 1, 3, or 7 days. Within 1 day of HFD, BAT weight and lipid content were increased. HFD also immediately reduced insulin-stimulated glucose uptake by BAT, indicating rapid induction of insulin resistance. This was accompanied by a tendency toward a reduced uptake of triglyceride-derived fatty acids by BAT. Mitochondrial mass and Ucp1 expression were unaltered, whereas after 3 days of HFD, markers of mitochondrial dynamics suggested induction of a more fused mitochondrial network. Additionally, HFD also increased macrophage markers in BAT after 3 days of HFD. Counterintuitively, the switch to HFD was accompanied by an acute rise in core body temperature. We showed that a single day of HFD feeding is sufficient to induce the first signs of whitening and insulin resistance in BAT, which reduces the uptake of glucose and triglyceride-derived fatty acids. BAT whitening and insulin resistance are likely sustained by reduced mitochondrial oxidation due to changes in mitochondrial dynamics and macrophage infiltration, respectively. Likely, the switch to HFD swiftly induces thermogenesis in other metabolic organs, which allows attenuation of BAT thermogenesis.

    Dairy farmers' strategies in four European countries before and after abolition of the milk quota
    Klopčič, Marija ; Kuipers, Abele ; Malak-Rawlikowska, Agata ; Stalgiene, Aldona ; Ule, Anita ; Erjavec, Karmen - \ 2019
    Land Use Policy 88 (2019). - ISSN 0264-8377
    Dairy farmers - EU countries - Milk quota abolition - Strategies

    In recent years, the European Union (EU) dairy sector has experienced considerable changes, triggering heavily fluctuating milk prices and a crash in milk prices in 2015/2016. These changes were forcing dairy farmers to respond by reconsidering their strategy. Since there is a lack of insight into how farmers were adjusting their strategies to the new circumstances, this study aimed to fill the gap by conducting a survey on farmers’ development plans in three Central and Eastern European countries (Poland, Lithuania and Slovenia) with different farming systems and one Western European country with a well-developed dairy sector (the Netherlands) before (2010 and 2013) and one year after the EU milk quota was abolished (2016). Groups of farmers with similar strategies were identified using principle component analysis and cluster analysis. Differences in strategies between years and countries were studied. The results reveal three main strategies in the analysed years: expansion, specialisation, and wait and see. Six farmer clusters were then identified. The cluster of Growers was largest, corresponding to the strategies of expansion and specialisation in dairy production. The share of Growers was increasing in Poland and the Netherlands and falling in Lithuania and Slovenia, probably due to the strong market orientation and good dairy production conditions in the aforementioned countries. The share of farmers in the Wait and See cluster grew significantly from 2013 to 2016 in all countries. These farmers considered the economic environment as too uncertain for further development at the time. The share of Diversifiers was rather stable within each country over the years. The share of Chain integrators, namely those who look for cooperation with other parties in the chain, was larger in good years and the share of Co-operators, who prefer to cooperate with other farmers, was larger in difficult market times. The cluster of Movers had the largest farms. On average, larger farms with somewhat younger farmers opted for growth, chain integration or moving and somewhat older farmers with smaller farms for a (temporary) stand-still. But considerable differences in the number of farmers per cluster over the years were found. Less than half the farmers were consistent in their development direction after 3 years, due to fluctuating prices and changing policies. Wait and See farmers were the most consistent. Policymakers and advisory services should consider farm strategies according to national specificities. Most farmers follow a strategy of expansion, while a smaller group of them were more concerned and act cautiously in a difficult market or policy situation. However, many farmers appeared to change their opinion on the self-chosen direction from time to time due to the varying circumstances. This instability in strategy choice makes future decision-making a fluid matter and not really consistent with well-designed planning.

    Data from: Implications of shared predation for space use in two sympatric leporids
    Weterings, M.J.A. ; Ewert, Sophie P. ; Peereboom, Jeffrey N. ; Kuipers, Henry J. ; Kuijper, Dries P.J. ; Prins, H.H.T. ; Jansen, P.A. ; Langevelde, F. van; Wieren, S.E. van - \ 2019
    Wageningen University & Research
    alternative prey - habitat characteristics - habitat riskiness - residence time - space race - vegetation structure - Lepus europaeus - Oryctolagus cuniculus - Vulpes vulpes
    Spatial variation in habitat riskiness has a major influence on the predator–prey space race. However, the outcome of this race can be modulated if prey shares enemies with fellow prey (i.e., another prey species). Sharing of natural enemies may result in apparent competition, and its implications for prey space use remain poorly studied. Our objective was to test how prey species spend time among habitats that differ in riskiness, and how shared predation modulates the space use by prey species. We studied a one‐predator, two‐prey system in a coastal dune landscape in the Netherlands with the European hare (Lepus europaeus) and European rabbit (Oryctolagus cuniculus) as sympatric prey species and red fox (Vulpes vulpes) as their main predator. The fine‐scale space use by each species was quantified using camera traps. We quantified residence time as an index of space use. Hares and rabbits spent time differently among habitats that differ in riskiness. Space use by predators and habitat riskiness affected space use by hares more strongly than space use by rabbits. Residence time of hare was shorter in habitats in which the predator was efficient in searching or capturing prey species. However, hares spent more time in edge habitat when foxes were present, even though foxes are considered ambush predators. Shared predation affected the predator–prey space race for hares positively, and more strongly than the predator–prey space race for rabbits, which were not affected. Shared predation reversed the predator–prey space race between foxes and hares, whereas shared predation possibly also released a negative association and promoted a positive association between our two sympatric prey species. Habitat riskiness, species presence, and prey species’ escape mode and foraging mode (i.e., central‐place vs. noncentral‐place forager) affected the prey space race under shared predation.
    Implications of shared predation for space use in two sympatric leporids
    Weterings, Martijn J.A. ; Ewert, Sophie P. ; Peereboom, Jeffrey N. ; Kuipers, Henry J. ; Kuijper, Dries P.J. ; Prins, Herbert H.T. ; Jansen, Patrick A. ; Langevelde, Frank van; Wieren, Sipke E. van - \ 2019
    Ecology and Evolution 9 (2019)6. - ISSN 2045-7758 - p. 3457 - 3469.
    Spatial variation in habitat riskiness has a major influence on the predator–prey space race. However, the outcome of this race can be modulated if prey shares enemies with fellow prey (i.e., another prey species). Sharing of natural enemies may result in apparent competition, and its implications for prey space use remain poorly studied. Our objective was to test how prey species spend time among habitats that differ in riskiness, and how shared predation modulates the space use by prey species. We studied a one‐predator, two‐prey system in a coastal dune landscape in the Netherlands with the European hare (Lepus europaeus) and European rabbit (Oryctolagus cuniculus) as sympatric prey species and red fox (Vulpes vulpes) as their main predator. The fine‐scale space use by each species was quantified using camera traps. We quantified residence time as an index of space use. Hares and rabbits spent time differently among habitats that differ in riskiness. Space use by predators and habitat riskiness affected space use by hares more strongly than space use by rabbits. Residence time of hare was shorter in habitats in which the predator was efficient in searching or capturing prey species. However, hares spent more time in edge habitat when foxes were present, even though foxes are considered ambush predators. Shared predation affected the predator–prey space race for hares positively, and more strongly than the predator–prey space race for rabbits, which were not affected. Shared predation reversed the predator–prey space race between foxes and hares, whereas shared predation possibly also released a negative association and promoted a positive association between our two sympatric prey species. Habitat riskiness, species presence, and prey species’ escape mode and foraging mode (i.e., central‐place vs. noncentral‐place forager) affected the prey space race under shared predation.
    Renaissance of traditional DNA transfer strategies for improvement of industrial lactic acid bacteria
    Bron, Peter A. ; Marcelli, Barbara ; Mulder, Joyce ; Els, Simon van der; Morawska, Luiza P. ; Kuipers, Oscar P. ; Kok, Jan ; Kleerebezem, Michiel - \ 2019
    Current Opinion in Biotechnology 56 (2019). - ISSN 0958-1669 - p. 61 - 68.

    The ever-expanding genomic insight in natural diversity of lactic acid bacteria (LAB) has revived the industrial interest in traditional and natural genetic mobilization methodologies. Here, we review recent advances in horizontal gene transfer processes in LAB, including natural competence, conjugation, and phage transduction. In addition, we envision the possibilities for industrial strain improvement arising from the recent discoveries of molecular exchanges between bacteria through nanotubes and extracellular vesicles, as well as the constantly expanding genome editing possibilities using the CRISPR-Cas technology.

    Induction of Natural Competence in Genetically-modified Lactococcus lactis
    Mulder, Joyce ; Wels, Michiel ; Kuipers, Oscar ; Kleerebezem, Michiel ; Bron, Peter - \ 2018
    Bio-protocol 8 (2018)13. - ISSN 2331-8325

    Making salt water drinkable
    Kuipers, N.J.M. - \ 2018
    Zout water drinkbaar maken
    Kuipers, N.J.M. ; Tongeren, W.G.J.M. van - \ 2018
    IL-37 expression reduces lean body mass in mice by reducing food intake
    Kuipers, Eline N. ; Dam, Andrea D. van; Ballak, Dov B. ; Wit, Ellemiek A. de; Dinarello, Charles A. ; Stienstra, Rinke ; Diepen, Janna A. van; Rensen, Patrick C.N. ; Boon, Mariëtte R. - \ 2018
    International Journal of Molecular Sciences 19 (2018)8. - ISSN 1661-6596
    Energy metabolism - Food intake - High fat diet - IL-37

    The human cytokine interleukin (IL)-37 is an anti-inflammatory member of the IL-1 family of cytokines. Transgenic expression of IL-37 in mice protects them from diet-induced obesity and associated metabolic complications including dyslipidemia, inflammation and insulin resistance. The precise mechanism of action leading to these beneficial metabolic effects is not entirely known. Therefore, we aimed to assess in detail the effect of transgenic IL-37 expression on energy balance, including food intake and energy expenditure. Feeding homozygous IL-37 transgenic mice and wild-type (WT) control mice a high-fat diet (HFD; 45% kcal palm fat) for 6 weeks showed that IL-37 reduced body weight related to a marked decrease in food intake. Subsequent mechanistic studies in mice with heterozygous IL-37 expression versus WT littermates, fed the HFD for 18 weeks, confirmed that IL-37 reduces food intake, which led to a decrease in lean body mass, but did not reduce fat mass and plasma lipid levels or alterations in energy expenditure independent of lean body mass. Taken together, this suggests that IL-37 reduces lean body mass by reducing food intake.

    In vivo selection of sfGFP variants with improved and reliable functionality in industrially important thermophilic bacteria
    Frenzel, Elrike ; Legebeke, Jelmer ; Stralen, Atze Van; Kranenburg, Richard Van; Kuipers, Oscar P. - \ 2018
    Biotechnology for Biofuels 11 (2018)1. - ISSN 1754-6834
    Biotechnology - Cyan - FACS - Geobacillus sp. - GFP - In vivo application - Parageobacillus sp. - Protein engineering - sfGFP - Thermophilic bacteria - Thermostability - Yellow
    Background: Fluorescent reporter proteins (FP) have become an indispensable tool for the optimization of microbial cell factories and in synthetic biology per se. The applicability of the currently available FPs is, however, constrained by species-dependent performance and misfolding at elevated temperatures. To obtain functional reporters for thermophilic, biotechnologically important bacteria such as Parageobacillus thermoglucosidasius, an in vivo screening approach based on a mutational library of superfolder GFP was applied. Results: Flow cytometry-based benchmarking of a set of GFPs, sfGFPs and species-specific codon-optimized variants revealed that none of the proteins was satisfyingly detectable in P. thermoglucosidasius at its optimal growth temperature of 60 °C. An undirected mutagenesis approach coupled to fluorescence-activated cell sorting allowed the isolation of sfGFP variants that were extremely well expressed in the chassis background at 60 °C. Notably, a few nucleotide substitutions, including silent mutations, significantly improved the functionality and brightness. The best mutant sfGFP(N39D/A179A) showed an 885-fold enhanced mean fluorescence intensity (MFI) at 60 °C and is the most reliable reporter protein with respect to cell-to-cell variation and signal intensity reported so far. The in vitro spectral and thermostability properties were unaltered as compared to the parental sfGFP protein, strongly indicating that the combination of the amino acid exchange and an altered translation or folding speed, or protection from degradation, contribute to the strongly improved in vivo performance. Furthermore, sfGFP(N39D/A179A) and the newly developed cyan and yellow derivatives were successfully used for labeling several industrially relevant thermophilic bacilli, thus proving their broad applicability. Conclusions: This study illustrates the power of in vivo isolation of thermostable proteins to obtain reporters for highly efficient fluorescence labeling. Successful expression in a variety of thermophilic bacteria proved that the novel FPs are highly suitable for imaging and flow cytometry-based studies. This enables a reliable cell tracking and single-cell-based real-time monitoring of biological processes that are of industrial and biotechnological interest.
    Intermodality and synchromodality
    Tavasszy, L. ; Behdani, B. ; Konings, Rob - \ 2018
    In: Ports and Networks - Strategies, Operations and Perspectives / Geerlings, Harry, Kuipers, Bart, Zuidwijk, Rob, Oxon : Routledge - ISBN 9781472485007 - p. 251 - 266.
    Transport networks have evolved from multimodal networks towards integrated networks allowing for intermodal transport – the carriage of a single load unit by consecutive modes in a transport chain. Synchromodality (or synchronized intermodality) – as the next stage in port/hinterland network development – can be briefly summarized as the vision of a network of well-synchronized and interconnected transport modes, which together cater for the aggregate transport demand and can dynamically adapt to the individual and instantaneous needs of network users. The objective of the chapter is to introduce the idea of Synchromodality. We discuss the current position and evolution of intermodal hinterland transport systems. Next, we describe the main elements of a synchronized intermodal transport system and the innovations that are necessary to arrive at synchromodal transport systems. We further describe the barriers for future development including technological, economical and institutional aspects.
    Dairy farmers’ business strategies in Central and Eastern Europe based on evidence from Lithuania, Poland and Slovenia
    Verhees, Frans ; Malak-Rawlikowska, Agatsa ; Stalgiene, Aldona ; Kuipers, Abele ; Klopčič, Marija - \ 2018
    Italian Journal of Animal Science 17 (2018)3. - ISSN 1594-4077 - p. 755 - 766.
    To evaluate market-oriented strategic decision-making by farmers in Central and Eastern Europe (CEE) farm development paths of dairy farmers in Slovenia, Poland and Lithuania were analysed. The influence of internal strengths and weaknesses, external opportunities and threats, and farmer goals on strategic choices and performance were explored. Principal component, hierarchical cluster and regression analyses were performed to test the conceptual framework. Seven strategic groups emerged with specific development paths, that is, Wait and see, Movers, Chain integrators, Specializers and Diversifiers. The latter two split into cooperative and independent groups. Maximisation of profit and sustainable farming ranked highest as farming goals. Availability of land and labour were weaknesses for all strategic groups in all countries. External opportunities and threats varied between countries and to a lesser degree between strategic groups. The Wait and see and Cooperating diversifier groups gave less optimistic scores than other strategic groups. The attitudes of CEE farmers towards the market and future Common Agricultural Policy remain more negative than those of a group of Western European farmers. The results of this study confirm that internal strengths and weaknesses, external opportunities and threats, together with farmers’ goals and strategies influence farmer performance, but independently of each other. Strategies do not appear to be a mediating variable between the internal and external environment of the farm and the performance of the farm. Policy makers, companies and extension workers should take the heterogeneity in strategic development into account when dealing with these and similar groups of farms.
    CorNet: Assigning function to networks of co-evolving residues by automated literature mining
    Bergh, Tom Van Den; Tamo, Giorgio ; Nobili, Alberto ; Tao, Yifeng ; Tan, Tianwei ; Bornscheuer, Uwe T. ; Kuipers, Remko K.P. ; Vroling, Bas ; Jong, René M. De; Subramanian, Kalyanasundaram ; Schaap, Peter J. ; Desmet, Tom ; Nidetzky, Bernd ; Vriend, Gert ; Joosten, Henk-Jan - \ 2017
    PLoS ONE 12 (2017)5. - ISSN 1932-6203 - p. e0176427 - e0176427.
    CorNet is a web-based tool for the analysis of co-evolving residue positions in protein super-family sequence alignments. CorNet projects external information such as mutation data extracted from literature on interactively displayed groups of co-evolving residue positions to shed light on the functions associated with these groups and the residues in them. We used CorNet to analyse six enzyme super-families and found that groups of strongly co-evolving residues tend to consist of residues involved in a same function such as activity, specificity, co-factor binding, or enantioselectivity. This finding allows to assign a function to residues for which no data is available yet in the literature. A mutant library was designed to mutate residues observed in a group of co-evolving residues predicted to be involved in enantioselectivity, but for which no literature data is available yet. The resulting set of mutations indeed showed many instances of increased enantioselectivity.
    Analysis of Stakeholders’ Expectations for Dairy Sector Development Strategies from a Central Eastern and Western European Perspective
    Kuipers, A. ; Malak-Rewlikowska, Agata ; Stalgiene, Aldona ; Klopčič, Marija - \ 2017
    German Journal of Agricultural Economics 66 (2017)4. - ISSN 0002-1121 - p. 265 - 280.
    The development paths chosen by farmers and the critical success factors involved can be better understood when the business context in which these farmers operate is known. Also, interaction in the chain contributes to the strength of the chain. This raises questions such as do chain parties cooperate and is there a certain consensus concerning the future strategic route? This article provides a unique analysis of how stakeholders envisage the future of dairy farming in a period of radical policy change and what barriers they foresee to their objectives. The questionnaire used examined perceptions on development strategies, availability of resources, opportunities & threats (O&T), farmer skills and future expectations. In 2015 and early 2016, a total of 161 completed questionnaires were collected from stakeholders (leading persons in the dairy chain) in the Netherlands, Slovenia, Lithuania and Poland. Data were analysed by PCA, ANOVA, cluster and stepwise regression methods. Eight strategic clusters of stakeholders were found. Farm expansion and specialisation was the most expected development strategy (57% of stakeholders). Almost one fourth of the stakeholders took a wait and see approach, of which 15% looked for opportunities to activate at a particular moment in time, while 8% were generally pessimistic about the future. Diversification in combination with organic farming was chosen by 5% of the stakeholders, 10% of stakeholders focused on cooperation, service and high tech, and another 5% placed their trust in skills, subsidies and labour. The opinions of stakeholders were highly affected by the country of origin, while only minor variations in opinions were observed between different categories of stakeholders. Polish stakeholders showed the most specialised view on the dairy chain, but they scored relatively low on cooperation. Development towards diversification and organic agriculture received higher scores in Slovenia and Lithuania compared to the Netherlands and especially to Poland. Netherlands’ stakeholders were the most positive about the future e.g. they foresee expansion and market opportunities. It was shown that strategies, resources and O&T each directly affect future expectations, which was in agreement with the hypothetical model used.
    Editorial: Lactic acid bacteria - a continuing journey in science and application
    Kleerebezem, M. ; Kuipers, O.P. ; Smid, E.J. - \ 2017
    FEMS Microbiology Reviews 41 (2017)Supp 1. - ISSN 0168-6445 - p. S1 - S2.
    Unleashing natural competence in Lactococcus lactis by induction of the competence regulator ComX
    Mulder, Joyce ; Wels, Michiel ; Kuipers, Oscar P. ; Kleerebezem, Michiel ; Bron, Peter A. - \ 2017
    Applied and Environmental Microbiology 83 (2017)20. - ISSN 0099-2240 - 13 p.
    Comparative genomics - Lactococcus lactis - Natural competence

    In biotechnological workhorses like Streptococcus thermophilus and Bacillus subtilis, natural competence can be induced, which facilitates genetic manipulation of these microbes. However, in strains of the important dairy starter Lactococcus lactis, natural competence has not been established to date. However, in silico analysis of the complete genome sequences of 43 L. lactis strains revealed complete late competence gene sets in 2 L. lactis subsp. cremoris strains (KW2 and KW10) and at least 10 L. lactis subsp. lactis strains, including the model strain IL1403 and the plant-derived strain KF147. The remainder of the strains, including all dairy isolates, displayed genomic decay in one or more of the late competence genes. Nisincontrolled expression of the competence regulator comX in L. lactis subsp. lactis KF147 resulted in the induction of expression of the canonical competence regulon and elicited a state of natural competence in this strain. In contrast, comX expression in L. lactis NZ9000, which was predicted to encode an incomplete competence gene set, failed to induce natural competence. Moreover, mutagenesis of the comEA-EC operon in strain KF147 abolished the comX-driven natural competence, underlining the involvement of the competence machinery. Finally, introduction of nisininducible comX expression into nisRK-harboring derivatives of strains IL1403 and KW2 allowed the induction of natural competence in these strains also, expanding this phenotype to other L. lactis strains of both subspecies.

    ANGPTL4 promotes bile acid absorption during taurocholic acid supplementation via a mechanism dependent on the gut microbiota
    Janssen, Aafke W.F. ; Dijk, Wieneke ; Boekhorst, Jos ; Kuipers, Folkert ; Groen, Albert K. ; Lukovac, Sabina ; Hooiveld, Guido J.E.J. ; Kersten, Sander - \ 2017
    Biochimica et Biophysica Acta. Molecular and Cell Biology of Lipids 1862 (2017)10. - ISSN 1388-1981 - p. 1056 - 1067.
    Angiopoietin-like 4 - Antibiotics - Bile acids - Gut microbiota - Lipoprotein lipase - Triglycerides
    Angiopoietin-like 4 (ANGPTL4) raises plasma triglyceride levels by inhibiting lipoprotein lipase. A set of compounds that are able to reduce plasma triglyceride levels are bile acids (BA). Because BA have been shown to decrease ANGPTL4 secretion by intestinal cells, we hypothesized that BA lower plasma triglycerides (partly) via ANGPTL4. To test that hypothesis, wild-type and Angptl4−/− mice were fed chow supplemented with taurocholic acid (TCA) for seven days. TCA supplementation effectively lowered plasma triglycerides in wild-type and Angptl4−/− mice, indicating that ANGPTL4 is not required for plasma triglyceride-lowering by BA. Intriguingly, however, plasma and hepatic BA concentrations were significantly lower in TCA-supplemented Angptl4−/− mice than in TCA-supplemented wild-type mice. These changes in the Angptl4−/− mice were accompanied by lower BA levels in ileal scrapings and decreased expression of FXR-target genes in the ileum, including the BA transporter Slc10a2. By contrast, faecal excretion of specifically primary BA was higher in the Angptl4−/− mice, suggesting that loss of ANGPTL4 impairs intestinal BA absorption. Since the gut microbiota converts primary BA into secondary BA, elevated excretion of primary BA in Angptl4−/− mice may reflect differences in gut microbial composition and/or functionality. Indeed, colonic microbial composition was markedly different between Angptl4−/− and wild-type mice. Suppression of the gut bacteria using antibiotics abolished differences in plasma, hepatic, and faecal BA levels between TCA-supplemented Angptl4−/− and wild-type mice. In conclusion, 1) ANGPTL4 is not involved in the triglyceride-lowering effect of BA; 2) ANGPTL4 promotes BA absorption during TCA supplementation via a mechanism dependent on the gut microbiota.
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