Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Records 1 - 20 / 521

  • help
  • print

    Print search results

  • export
    A maximum of 250 titles can be exported. Please, refine your queryYou can also select and export up to 30 titles via your marked list.
  • alert
    We will mail you new results for this query: q=Smid
Check title to add to marked list
A European inter-laboratory trial to evaluate the performance of three serological methods for diagnosis of Mycoplasma bovis infection in cattle using latent class analysis
Andersson, Anna Maria ; Aspán, Anna ; Wisselink, Henk J. ; Smid, Bregtje ; Ridley, Anne ; Pelkonen, Sinikka ; Autio, Tiina ; Lauritsen, Klara Tølbøll ; Kensø, Jane ; Gaurivaud, Patrice ; Tardy, Florence - \ 2019
BMC Veterinary Research 15 (2019)1. - ISSN 1746-6148 - 1 p.
ELISA - Inter-laboratory trial - Latent class analysis - Mycoplasma bovis cattle - Western blot

BACKGROUND: Mycoplasma bovis (M. bovis) is an emerging bovine pathogen, leading to significant economic losses in the livestock industry worldwide. Infection can result in a variety of clinical signs, such as arthritis, pneumonia, mastitis and keratoconjunctivitis, none of which are M. bovis-specific. Laboratory diagnosis is therefore important. Serological tests to detect M. bovis antibodies is considered an effective indicator of infection in a herd and often used as a herd test. Combined with clinical judgement, it can also be used to implement control strategies and/or to estimate the disease prevalence within a country. However, due to lack of harmonisation of approaches to testing, and serological tests used by different laboratories, comparisons of prevalence data between countries is often difficult. A network of researchers from six European countries designed and participated in an inter-laboratory trial, with the aim of evaluating the sensitivity (Se) and specificity (Sp) of two commercially available ELISA tests (ID Screen® ELISA (IDvet) and BIO K302 ELISA (BIO-X Diagnostics)) for diagnosis of M. bovis infection. Each laboratory received a blinded panel of bovine sera and tested independently, according to manufacturer's instructions. Western blot analyses (WB) performed by one of the participating laboratories was used as a third diagnostic test in the statistical evaluation of Se and Sp values using latent class analysis. RESULTS: The Se of WB, the ID Screen® ELISA and the BIO K302 ELISA were determined to be 91.8, 93.5 and 49.1% respectively, and corresponding Sp of the three tests were 99.6, 98.6 and 89.6%, respectively. CONCLUSIONS: The present study is, to our knowledge, the first to present an inter-laboratory comparison of the BIO K302 ELISA and the ID Screen® ELISA. Based on our results, the ID Screen® ELISA showed high consistency with WB and performed with higher precision and accuracy than the BIO K302 ELISA.

Fermented cereal-based Munkoyo beverage: Processing practices, microbial diversity and aroma compounds
Phiri, Sydney ; Schoustra, Sijmen E. ; Heuvel, Joost van den; Smid, Eddy J. ; Shindano, John ; Linnemann, Anita - \ 2019
PLoS ONE 14 (2019)10. - ISSN 1932-6203

Fermented cereal-based foods play a crucial role in attaining food and nutrition security for resource-poor populations in sub-Saharan Africa. These products are widely produced by spontaneous fermentation using of cereal grains as raw material. They have a unique taste and flavour, are rich sources of energy and their non-alcoholic nature makes them ideal for consumption by the entire population, including children. Lactic acid bacteria dominate the fermentation process and lead to a low pH of around 4, which suppresses the growth of pathogenic bacteria, thereby increasing the shelf-life and safety of the food. Knowledge about processing practices, consumption patterns and bacterial communities is essential to regulate processing and design appropriate mixes of micro-organisms to produce starter cultures for commercial production of standard-quality fermented foods that meet desired quality characteristics. In four regions of Zambia, we surveyed processing practices and consumption patterns of a spontaneously fermented cereal-based beverage called Munkoyo, commonly produced in Zambia and the Democratic Republic of Congo. Variations in processing practices exist in cooking time of the unfermented maize porridge and time allowed for fermentation. Consumption is mainly at household level and the product is considered as an energy drink. Characterisation of the bacterial communities of over 90 samples with 16S amplicon sequencing on DNA extracted from the entire bacterial community revealed six dominant families, namely Streptococcaceae, Leuconostocaceae, Enterobacteriaceae, Lactabacillales, Bacillaceae and Aeromonadaceae, and a Shannon index of up to 1.18 with an effective number of 3.44 bacterial species. Bacterial communities that underlie the fermentation in Munkoyo differ in their composition for the different regions using common processing steps, suggesting that different combinations of bacteria can be used to achieve successful Munkoyo fermentation. Analysis of aroma profiles in 15 different samples from two different Provinces showed that aldehydes, esters, organic acids, alkanes, alkenes and alcohols dominated.

Spontaneous fermentation of Munkoyo: a cereal-based beverage in Zambia
Phiri, Sydney - \ 2019
Wageningen University. Promotor(en): E.J. Smid; V. Fogliano, co-promotor(en): A.R. Linnemann; S.E. Schoustra. - Wageningen : Wageningen University - ISBN 9789463951296 - 112
Product optimization of Zambian traditionally fermented milk - mabisi
Moonga, Himoonga Bernard - \ 2019
Wageningen University. Promotor(en): E.J. Smid, co-promotor(en): S.E. Schoustra; A.R. Linnemann; J. Shindano. - Wageningen : Wageningen University - ISBN 9789463951289 - 115
Salt inactivation of classical swine fever virus and African swine fever virus in porcine intestines confirms the existing in vitro casings model
Jelsma, Tinka ; Wijnker, Joris J. ; Smid, Bregtje ; Verheij, Eline ; Poel, Wim H.M. van der; Wisselink, Henk J. - \ 2019
Veterinary Microbiology 238 (2019). - ISSN 0378-1135
3D collagen matrix model - African swine fever - Classical swine fever - D-values - Intestine - Virus inactivation

Natural casings, to be used as sausage containers, are being traded worldwide and may be contaminated with contagious viruses. Standard processing of such natural casings is by salt treatment with a duration of 30 days before shipment. Since information is lacking about the efficacy of these virus inactivation procedures, an in vitro 3D collagen matrix model, mimicking natural casings, was developed previously to determine the efficacy of salt to inactivate specific viruses. To validate this model, a comparison in vivo experiment was performed using intestines of pigs experimentally infected with African swine fever virus (ASFV) and classical swine fever virus (CSFV). Decimal reduction (D) values, were determined at 4 °C, 12 °C, 20 °C and 25 °C. The standard salt processing procedure showed an efficient inactivation of ASFV and CSFV over time in a temperature dependent way. Dintestine values of both viruses, treated with the standard salt treatment, were in line with the Dcollagen values. It was concluded that these results underline the suitability of the 3D collagen matrix model to determine virus inactivation and to replace animal experiments. Furthermore, an increase in storage time for standard salt processed casings derived from CSFV endemic regions is highly recommended for an efficient inactivation of CSFV.

Fermenteren is populair, 'maar het proces luistert nauw'
Smid, E.J. - \ 2019
Fermentations great promise
Smid, Eddy - \ 2019
biobased economy - microorganisms - bacteria - chemicals - food - fatty acids - kerosene - fermentation
Species- and size-related differences in dopamine-like immunoreactive clusters in the brain of Nasonia vitripennis and N. giraulti
Groothuis, Jitte ; Heuvel, Krista van den; Smid, Hans M. - \ 2019
Cell and Tissue Research (2019). - ISSN 0302-766X - 13 p.
Brain - Confocal laser scanning microscopy - Dopamine - Insect - Parasitic wasp

An extreme reduction in body size has been shown to negatively impact the memory retention level of the parasitic wasp Nasonia vitripennis. In addition, N. vitripennis and Nasonia giraulti, closely related parasitic wasps, differ markedly in the number of conditioning trials required to form long-term memory. These differences in memory dynamics may be associated with differences in the dopaminergic neurons in the Nasonia brains. Here, we used dopamine immunoreactivity to identify and count the number of cell bodies in dopaminergic clusters of normal- and small-sized N. vitripennis and normal-sized N. giraulti. We counted in total a maximum of approximately 160 dopaminergic neurons per brain. These neurons were present in 9 identifiable clusters (D1a, D1b, D2, D3, D4a, D4b, D5, D6 and D7). Our analysis revealed that N. giraulti had fewer cells in the D2 and D4a clusters but more in D4b, compared with normal-sized N. vitripennis. In addition, we found fewer cells in the D5 and D7 cluster of small-sized N. vitripennis compared to normal-sized N. vitripennis. A comparison of our findings with the literature on dopaminergic clusters in the fruit fly Drosophila melanogaster and the honey bee Apis mellifera indicates that clusters D2, D3 and D5 may play a role in memory formation in Nasonia wasps. The results from both the species comparison and the size comparison are therefore of high interest and importance for our understanding of the complex intricacies that underlie the memory dynamics of insects.

Long-chain vitamin K2 production in Lactococcus lactis is influenced by temperature, carbon source, aeration and mode of energy metabolism
Liu, Yue ; Bennekom, Eric O. Van; Zhang, Yu ; Abee, Tjakko ; Smid, Eddy J. - \ 2019
Microbial Cell Factories 18 (2019)1. - ISSN 1475-2859
Aeration - Carbon source - Long-chain MKs - Menaquinone - Natural enrichment - Respiration - Vitamin K2

Background: Vitamin K2 (menaquinone, MK-n) is a lipid-soluble vitamin that functions as a carboxylase co-factor for maturation of proteins involved in many vital physiological processes in humans. Notably, long-chain vitamin K2 is produced by bacteria, including some species and strains belonging to the group of lactic acid bacteria (LAB) that play important roles in food fermentation processes. This study was performed to gain insights into the natural long-chain vitamin K2 production capacity of LAB and the factors influencing vitamin K2 production during cultivation, providing a basis for biotechnological production of vitamin K2 and in situ fortification of this vitamin in food products. Results: We observed that six selected Lactococcus lactis strains produced MK-5 to MK-10, with MK-8 and MK-9 as the major MK variant. Significant diversities between strains were observed in terms of specific concentrations and titres of vitamin K2. L. lactis ssp. cremoris MG1363 was selected for more detailed studies of the impact of selected carbon sources tested under different growth conditions [i.e. static fermentation (oxygen absent, heme absent); aerobic fermentation (oxygen present, heme absent) and aerobic respiration (oxygen present, heme present)] on vitamin K2 production in M17 media. Aerobic fermentation with fructose as a carbon source resulted in the highest specific concentration of vitamin K2: 3.7-fold increase compared to static fermentation with glucose, whereas aerobic respiration with trehalose resulted in the highest titre: 5.2-fold increase compared to static fermentation with glucose. When the same strain was applied to quark fermentation, we consistently observed that altered carbon source (fructose) and aerobic cultivation of the pre-culture resulted in efficient vitamin K2 fortification in the quark product. Conclusions: With this study we demonstrate that certain LAB strains can be employed for efficient production of long-chain vitamin K2. Strain selection and optimisation of growth conditions offer a viable strategy towards natural vitamin K2 enrichment of fermented foods, and to improved biotechnological vitamin K2 production processes.

The Jewel Wasp Standard Brain: Average shape atlas and morphology of the female Nasonia vitripennis brain
Groothuis, J. ; Pfeiffer, K. ; Jundi, B. el; Smid, Hans M. - \ 2019
Arthropod Structure & Development 51 (2019). - ISSN 1467-8039 - p. 41 - 51.
Confocal laser scanning microscopy - Iterative shape averaging - Nasonia vitripennis - Parasitic wasp - Standard brain

Nasonia, a genus of parasitoid wasps, is a promising model system in the study of developmental and evolutionary genetics, as well as complex traits such as learning. Of these “jewel wasps”, the species Nasonia vitripennis is widely spread and widely studied. To accelerate neuroscientific research in this model species, fundamental knowledge of its nervous system is needed. To this end, we present an average standard brain of recently eclosed naïve female N. vitripennis wasps obtained by the iterative shape averaging method. This “Jewel Wasp Standard Brain” includes the optic lobe (excluding the lamina), the anterior optic tubercle, the antennal lobe, the lateral horn, the mushroom body, the central complex, and the remaining unclassified neuropils in the central brain. Furthermore, we briefly describe these well-defined neuropils and their subregions in the N. vitripennis brain. A volumetric analysis of these neuropils is discussed in the context of brains of other insect species. The Jewel Wasp Standard Brain will provide a framework to integrate and consolidate the results of future neurobiological studies in N. vitripennis. In addition, the volumetric analysis provides a baseline for future work on age- and experience-dependent brain plasticity.

Development of a low-alcoholic fermented beverage employing cashew apple juice and non-conventional yeasts
Gamero, Amparo ; Ren, Xiao ; Lamboni, Yendouban ; Jong, Catrienus de; Smid, Eddy J. ; Linnemann, Anita R. - \ 2019
Fermentation 5 (2019)3. - ISSN 2311-5637
Alcoholic beverages - Aroma profile - Cashew apple juice - Hanseniaspora guilliermondii - Non‐conventional yeasts - Saccharomyces cerevisiae - Torulaspora microellipsoides

Cashew apples are by‐products in the production of cashew nuts, which are mostly left to rot in the fields. Cashew apple juice (CAJ), a highly nutritious beverage, can be produced from them. It is rich in sugars and ascorbic acid, but its high polyphenol content makes it bitter and astringent, and therefore difficult to commercialize. The kingdom of fungi contains more than 2000 yeast species, of which only a few species have been studied in relation to their potential to produce aroma compounds. The aim of this research was to develop a new low‐alcoholic fermented beverage to valorize cashew apples. For this purpose, a screening was carried out employing non‐conventional yeast species and some species of the genus Saccharomyces for comparison, followed by a more detailed study with four selected strains cultured at different conditions. The production of volatile aroma compounds as a function of the presence of oxygen, temperature, and yeast species was investigated. The results showed that the more diverse aroma profiles appeared at 25 °C under anaerobic cultivation conditions, where Saccharomyces cerevisiae WUR 102 and Hanseniaspora guilliermondii CBS 2567 excelled in the synthesis of certain aroma compounds, such as β-phenylethanol and its acetate ester (rose aroma). Further studies are needed to test consumer acceptance of these new products.

Microbial communities in a dynamic in vitro model for the human ileum resemble the human ileal microbiota
Stolaki, Maria ; Minekus, Mans ; Venema, Koen ; Lahti, Leo ; Smid, Eddy J. ; Kleerebezem, Michiel ; Zoetendal, Erwin G. - \ 2019
FEMS microbiology ecology 95 (2019)8. - ISSN 0168-6496
in vitro model - gut health - ileum - microbial diversity - microbiota - short chain fatty acids

The important role for the human small intestinal microbiota in health and disease has been widely acknowledged. However, the difficulties encountered in accessing the small intestine in a non-invasive way in healthy subjects have limited the possibilities to study its microbiota. In this study, a dynamic in vitro model that simulates the human ileum was developed, including its microbiota. Ileostomy effluent and fecal inocula were employed to cultivate microbial communities within the in vitro model. Microbial stability was repetitively achieved after 10 days of model operation with bacterial concentrations reaching on average 107 to 108 16S rRNA copy numbers/ml. High diversities similar to those observed in in vivo ileum samples were achieved at steady state using both fecal and ileostomy effluent inocula. Functional stability based on Short Chain Fatty Acid concentrations was reached after 10 days of operation using fecal inocula, but was not reached with ileostomy effluent as inoculum. Principal Components and cluster analysis of the phylogenetic profiles revealed that in vitro samples at steady state clustered closest to two samples obtained from the terminal ileum of healthy individuals, independent of the inoculum used, demonstrating that the in vitro microbiota at steady state resembles that of the human ileum.

Microbial community dynamics in traditionally fermented milk
Groenenboom, Anneloes E. - \ 2019
Wageningen University. Promotor(en): E.J. Smid; B.J. Zwaan, co-promotor(en): S.E. Schoustra; A.R. Linnemann. - Wageningen : Wageningen University - ISBN 9789463439664 - 146
Dynamic modelling of brewers’ yeast and Cyberlindnera fabianii co-culture behaviour for steering fermentation performance
Rijswijck, Irma M.H. van; Mastrigt, Oscar van; Pijffers, Gerco ; Wolkers–Rooijackers, Judith C.M. ; Abee, Tjakko ; Zwietering, Marcel H. ; Smid, Eddy J. - \ 2019
Food Microbiology 83 (2019). - ISSN 0740-0020 - p. 113 - 121.

Co-cultivation of brewers' yeast (Saccharomyces cerevisiae) with Cyberlindnera fabianii makes it possible to steer aroma and alcohol levels by changing the inoculation ratio of the two yeasts. A dynamic model was developed based on mono-culture performance of brewers' yeast and C. fabianii in controlled bioreactors with aerated wort as medium, describing growth rate, carbohydrate utilization, ethanol production, maintenance, oxygen consumption and ergosterol biosynthesis/use for cell membrane synthesis (the last one only for brewers' yeast). The parameters were estimated by fitting models to experimental data of both mono-cultivations. To predict the fermentation outcome of brewers' yeast and C. fabianii in co-cultivation, the two models were combined and the same parameter settings were used. The co-cultivation model was experimentally validated for the inoculum ratios 1:10 and 1:100 brewers' yeast over C. fabianii. The use of predictive modelling supported the hypothesis that performance of brewers' yeast in co-cultivation is inhibited by oxygen depletion which is required for the biosynthesis of ergosterol. This dynamic modelling approach and the parameters involved may also be used to predict the performance of brewers’ yeast in the co-cultivation with other yeast species and to give guidance to optimize the fermentation outcome.

No gains for bigger brains: Functional and neuroanatomical consequences of relative brain size in a parasitic wasp
Woude, Emma van der; Groothuis, Jitte ; Smid, Hans M. - \ 2019
Journal of Evolutionary Biology (2019). - ISSN 1010-061X
Heritable genetic variation in relative brain size can underlie the relationship between brain performance and the relative size of the brain. We used bidirectional artificial selection to study the consequences of genetic variation in relative brain size on brain morphology, cognition and longevity in Nasonia vitripennis parasitoid wasps. Our results show a robust change in relative brain size after 26 generations of selection and 6 generations of relaxation. Total average neuropil volume of the brain was 16% larger in wasps selected for relatively large brains than in wasps selected for relatively small brains, whereas the body length of the large‐brained wasps was smaller. Furthermore, the relative volume of the antennal lobes was larger in wasps with relatively large brains. Relative brain size did not influence olfactory memory retention, whereas wasps that were selected for larger relative brain size had a shorter longevity, which was even further reduced after a learning experience. These effects of genetic variation on neuropil composition and memory retention are different from previously described effects of phenotypic plasticity in absolute brain size. In conclusion, having relatively large brains may be costly for N. vitripennis, whereas no cognitive benefits were recorded.
Short communication: The effects of regrouping in relation to fresh feed delivery in lactating Holstein cows
Smid, Anne Marieke C. ; Weary, Daniel M. ; Bokkers, Eddie A.M. ; Keyserlingk, Marina A.G. von - \ 2019
Journal of Dairy Science 102 (2019)7. - ISSN 0022-0302 - p. 6545 - 6550.
management - mixing - social stress - welfare

This study tested whether separating regrouping from the time of fresh feed delivery mitigated the effects of regrouping on cow behavior and milk production. Cows (n = 26) were individually introduced into a stable group of 11 animals/pen fed twice daily. Animals were randomly assigned to early regrouping (at 0300 h, approximately 10.5 h after fresh feed delivery and 3.5 h before the next fresh feed delivery) and late regrouping (between 0630 and 0730 h, coinciding with access to fresh feed). For 3 d, starting immediately after regrouping, video recordings continuously monitored feeding and perching (i.e., standing with the 2 front feet in the lying stall) behavior and displacements at the feed bunk. Data loggers were used to quantify lying time and the number of standing bouts; milk production was automatically recorded at each milking. Daily feeding and lying times and the number of standing bouts per day did not differ between treatments or experimental days. Daily perching time and the number of displacements at the feed bunk did not differ between treatments but decreased with experimental day. Average milk production on d 2 and 3 after regrouping (30.6 ± 1.5 kg/d) was lower than during the 3 d before regrouping (32.3 ± 1.5 kg/d), but we observed no effect of treatment on this decline. We conclude that regrouping at a time not associated with fresh feed delivery does not mitigate the negative effects of regrouping.

Integrating parasitoid olfactory conditioning in augmentative biological control: Potential impact, possibilities, and challenges
Kruidhof, H.M. ; Kostenko, Olga ; Smid, Hans M. ; Vet, Louise E.M. - \ 2019
Frontiers in Ecology and Evolution 7 (2019). - ISSN 2296-701X
Associative learning - Foraging behavior - Natural enemies - Parasitoids - Searching efficacy

Despite the vast body of theoretical and empirical literature dealing with parasitoid learning, this knowledge has thus far rarely been exploited for manipulating the efficacy of augmentative biological pest control. This may be due to the fact that most studies on learning behavior were performed under laboratory conditions, whereas field trials remain scarce. However, the few studies that did investigate parasitoid foraging success under (semi-)field conditions show strong learning effects. Using so-called "parasitoid olfactory conditioning" (POC), parasitoids can be trained to become more efficient in the different phases involved in the process of host searching and host acceptance. POC can thus result in a "foraging efficacy gain", defined as the difference between the number of naive and conditioned parasitoids that need to be released to reach a certain parasitization level of the target-pest in the crop environment. This "gain" increases with an improved parasitoid learning ability and depends on the interplay between the parasitoid, crop, target-pest species and parasitoid rearing method. Moreover, the "foraging efficacy gain" depends on the technical implementation of POC, as this will determine the strength, duration and stability of the learning-induced behavioral change. In this perspective paper we will discuss (a) the conditions that can enhance the "foraging efficacy gain," (b) the possible approaches to implementation of POC and their costs and benefits, and (c) a stepwise approach to develop appropriate POC methods for the optimization of biological pest control.

Bacterial community dynamics in lait caillé, a traditional product of spontaneous fermentation from Senegal
Groenenboom, Anneloes E. ; Parker, Megan E. ; Vries, Anne De; Groot, Suzette de; Zobrist, Stephanie ; Mansen, Kimberly ; Milani, Peiman ; Kort, Remco ; Smid, Eddy J. ; Schoustra, Sijmen E. - \ 2019
PLoS ONE 14 (2019)5. - ISSN 1932-6203
Spontaneously fermented food products contain a complex, natural microbial community with potential probiotic activity. The addition of a health-promoting, probiotic bacterium to these products ensures the delivery of that probiotic activity to consumers. Here, we assess the microbial community of a traditional Senegalese milk product produced by spontaneous fermentation, called lait caillé. We produced the lait caillé in a traditional way and added a probiotic starter containing Lactobacillus rhamnosus yoba 2012 to the traditional process. We found various species that are known for their ability to ferment milk, including species from the genera Lactobacillus, Acetobacter, Lactococcus, and Streptococcus. Our results show that the addition of L. rhamnosus to the inoculum, can result in detectable levels of this strain in the final product, ranging between 0.2 and 1 percent of the total bacterial population. Subsequent rounds of fermentation using passive back-slopping without the addition of new L. rhamnosus led to a loss of this strain from the community of fermenting bacteria. Our results suggest that the addition of probiotic strains at every fermentation cycle can enrich the existing complex communities of traditionally fermented lait caillé while traditional bacterial strains remain dominant in the bacterial communities
Application of a partial cell recycling chemostat for continuous production of aroma compounds at near-zero growth rates
Mastrigt, Oscar van; Egas, Reinier A. ; Lillevang, Søren K. ; Abee, Tjakko ; Smid, Eddy J. - \ 2019
BMC Research Notes 12 (2019)1. - ISSN 1756-0500
Continuous cultivation - Fermentation - Lactic acid bacteria - Maintenance - Metabolomics - Retentostat - VOC

Objective: The partial cell recycling chemostat is a modification of the chemostat in which cells are partially recycled towards the bioreactor. This allows using dilution rates higher than the maximum growth rate resulting in higher biomass concentrations and increased process rates. In this study, we demonstrate with a single observation that this system can also be used to study microorganisms at near-zero growth rates and as production system for compounds specific for slow growth, such as those typical for ripened cheese. Results: Lactococcus lactis FM03-V2 was cultivated at growth rates between 0.0025 and 0.025 h -1 . Detailed analysis of produced aroma compounds revealed that levels of particular compounds were clearly affected by the growth rate within the studied range demonstrating that we can steer the aroma production by controlling the growth rate. With this approach, we also experimentally validated that the maintenance coefficient of this dairy strain decreased at near-zero growth rates (6.4-fold). An exponentially decreasing maintenance coefficient was included in the growth model, enabling accurate prediction of biomass accumulation in the partial cell recycling chemostat. This study demonstrates the potential of partial cell recycling chemostat both as aroma production system at near-zero growth rates and as unique research tool.

Data from: No gains for bigger brains: functional and neuroanatomical consequences of relative brain size in a parasitic wasp
Woude, E. van der; Groothuis, J. ; Smid, H.M. - \ 2019
artificial selection - trade-offs - constraints - insects - host-parasite interaction - bidirectional artificial selection - brain-size - appetitive olfactory conditioning - brain scaling - parasitic wasp - parasitoid - longevity - Nasonia vitripennis
Heritable genetic variation in relative brain size can underlie the relationship between brain performance and the relative size of the brain. We used bidirectional artificial selection to study the consequences of genetic variation in relative brain size on brain morphology, cognition and longevity in Nasonia vitripennis parasitoid wasps. Our results show a robust change in relative brain size after 26 generations of selection and 6 generations of relaxation. Total average neuropil volume of the brain was 16% larger in wasps selected for relatively large brains than in wasps selected for relatively small brains, whereas the body length of the large-brained wasps was smaller. Furthermore, the relative volume of the antennal lobes was larger in wasps with relatively large brains. Relative brain size did not influence olfactory memory retention, whereas wasps that were selected for larger relative brain size had a shorter longevity, which was even further reduced after a learning experience. These effects of genetic variation on neuropil composition and memory retention are different from previously described effects of phenotypic plasticity in absolute brain size. In conclusion, having relatively large brains may be costly for N. vitripennis, whereas no cognitive benefits were recorded.
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.