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.

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Evolution of plant growth and defense in a continental introduction
Agrawal, A.A. ; Hastings, A.P. ; Bradburst, G.S. ; Woods, E.C. ; Züst, T. ; Harvey, J.A. ; Bukovinszky, T. - \ 2015
American Naturalist 186 (2015)1. - ISSN 0003-0147 - p. E1 - E15.
milkweed asclepias-syriaca - loosestrife lythrum-salicaria - common milkweed - invasive populations - competitive ability - insect herbivores - chemical defenses - differentiation - specialist - selection
Substantial research has addressed adaptation of nonnative biota to novel environments, yet surprisingly little work has integrated population genetic structure and the mechanisms underlying phenotypic differentiation in ecologically important traits. We report on studies of the common milkweed Asclepias syriaca, which was introduced from North America to Europe over the past 400 years and which lacks most of its specialized herbivores in the introduced range. Using 10 populations from each continent grown in a common environment, we identified several growth and defense traits that have diverged, despite low neutral genetic differentiation between continents. We next developed a Bayesian modeling approach to account for relationships between molecular and phenotypic differences, confirming that continental trait differentiation was greater than expected from neutral genetic differentiation. We found evidence that growth-related traits adaptively diverged within and between continents. Inducible defenses triggered by monarch butterfly herbivory were substantially reduced in European populations, and this reduction in inducibility was concordant with altered phytohormonal dynamics, reduced plant growth, and a trade-off with constitutive investment. Freedom from the community of native and specialized herbivores may have favored constitutive over induced defense. Our replicated analysis of plant growth and defense, including phenotypically plastic traits, suggests adaptive evolution following a continental introduction.
Control of oriented cell division in the Arabidopsis embryo
Dop, M. van; Liao, C.Y. ; Weijers, D. - \ 2015
Current Opinion in Plant Biology 23 (2015). - ISSN 1369-5266 - p. 25 - 30.
preprophase band organization - plant development - transcription factor - monopteros - gene - root - differentiation - morphogenesis - cytokinesis - proteins
Multicellular plant development requires strict control of cell division orientation. A key unanswered question is how developmental regulators interact with the generic cell division machinery to trigger oriented divisions. We discuss the Arabidopsis embryo as a model for addressing this question. Recent progress in 3D imaging and computation now allows sketching of a framework for the developmental control of division orientation in which the signaling molecule auxin controls oriented division by preventing a geometrically defined default plane. We expect that the identification of auxin effectors, together with the identification of novel regulators of cell division will help to link developmental regulators to the division machinery.
A plant U-box protein, PUB4, regulates asymmetric cell division and cell proliferation in the root meristem
Kinoshita, A. ; Hove, C.A. ten; Tabata, R. ; Yamada, M. ; Shimizu, N. ; Ishida, T. ; Yamaguchi, K. ; Shigenobu, S. ; Takebayashi, Y. ; Luchies, J. ; Kobayashi, M. ; Kurata, T. ; Wada, T. ; Seo, M. ; Hasebe, M. ; Blilou, I. ; Fukuda, H. ; Scheres, B. ; Heidstra, R. ; Kamiya, Y. ; Sawa, S. - \ 2015
Development 142 (2015). - ISSN 0950-1991 - p. 444 - 453.
receptor-like kinase - arabidopsis shoot meristem - of-function phenotypes - cle peptides - gene-expression - repeat protein - differentiation - thaliana - organization - growth
The root meristem (RM) is a fundamental structure that is responsible for postembryonic root growth. The RM contains the quiescent center (QC), stem cells and frequently dividing meristematic cells, in which the timing and the frequency of cell division are tightly regulated. In Arabidopsis thaliana, several gain-of-function analyses have demonstrated that peptide ligands of the CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION-RELATED (CLE) family are important for maintaining RM size. Here, we demonstrate that a plant U-box E3 ubiquitin ligase, PUB4, is a novel downstream component of CLV3/CLE signaling in the RM. Mutations in PUB4 reduced the inhibitory effect of exogenous CLV3/CLE peptide on root cell proliferation and columella stem cell maintenance. Moreover, pub4 mutants grown without exogenous CLV3/CLE peptide exhibited characteristic phenotypes in the RM, such as enhanced root growth, increased number of cortex/endodermis stem cells and decreased number of columella layers. Our phenotypic and gene expression analyses indicated that PUB4 promotes expression of a cell cycle regulatory gene, CYCD6;1, and regulates formative periclinal asymmetric cell divisions in endodermis and cortex/endodermis initial daughters. These data suggest that PUB4 functions as a global regulator of cell proliferation and the timing of asymmetric cell division that are important for final root architecture.
AIL and HDG proteins act antagonistically to control cell proliferation
Horstman, A. ; Fukuoka, H. ; Muino Acuna, J.M. ; Nitsch, L.M.C. ; Guo, Changhao ; Passarinho, P.A. ; Sanchez Perez, G.F. ; Immink, R.G.H. ; Angenent, G.C. ; Boutilier, K.A. - \ 2015
Development 142 (2015). - ISSN 0950-1991 - p. 454 - 464.
arabidopsis-thaliana - transcription factors - plant transformation - ectopic expression - quantitative pcr - chip-seq - differentiation - genes - plethora - growth
AINTEGUMENTA-LIKE (AIL) transcription factors are key regulators of cell proliferation and meristem identity. Although AIL functions have been well described, the direct signalling components of this pathway are largely unknown.We show that BABY BOOM(BBM) and other AIL proteins physically interact with multiple members of the L1-expressed HOMEODOMAIN GLABROUS (HDG) transcription factor family, including HDG1, HDG11 and HDG12. Overexpression of HDG1, HDG11 and HDG12 restricts growth due to root and shoot meristem arrest, which is associated with reduced expression of genes involved in meristem development and cell proliferation pathways, whereas downregulation of multiple HDG genes promotes cell overproliferation. These results suggest a role for HDG proteins in promoting cell differentiation. We also reveal a transcriptional network in which BBM andHDG1regulate several common target genes, and whereBBM/AIL and HDG regulate the expression of each other. Taken together, these results suggest opposite roles for AIL and HDG proteins, with AILs promoting cell proliferation and HDGs stimulating cell differentiation, and that these functions are mediated at both the protein-protein interaction and transcriptional level.
Reduced fetal androgen exposure compromises Leydig cell function in adulthood
Teerds, K.J. ; Keijer, J. - \ 2015
Asian Journal of Andrology 17 (2015)2. - ISSN 1008-682X - p. 219 - 220.
differentiation
Disruption of normal fetal development can influence functioning of organs and cells in adulthood. Circumstantial evidence suggests that subtle reductions in fetal androgen production may be the cause of adult male reproductive disorders due to reduced testosterone production. The mechanisms through which these fetal events affect adult testosterone levels are largely unknown. A recent paper of Kilcoyne et al. provides evidence that fetal reduction in androgen production or signaling results in a reduced Leydig stems cell number after birth and concomitant Leydig cell failure in adulthood. This implies that fetal androgen deficiency can lead to negative programming of adult Leydig cell (ALC) function, which may have implications for general health, aging, and longevity.
Assessing the immunomodulatory potential of high-molecular-weight extracts from mushrooms; an assay based on THP-1 macrophages
Velde, J. van de; Wilbers, R.H.P. ; Westerhof, L.B. ; Raaij, D.R. van; Stavrakaki, I. ; Sonnenberg, A.S.M. ; Bakker, J. ; Schots, A. - \ 2015
Journal of the Science of Food and Agriculture 95 (2015)2. - ISSN 0022-5142 - p. 344 - 350.
monocytic leukemia-cells - agaricus-blazei murill - toll-like receptors - in-vitro - induction - responses - line - polysaccharides - differentiation - expression
BACKGROUND Food is a potential source of immunomodulating compounds that may be used to steer immune responses towards a desired status such as reducing inflammatory disorders. However, to identify and characterize such bioactive compounds, biologically relevant and standardized assays are required. Macrophages play an important role in immunomodulation and are suited for developing cell-based assays. An assay was developed based on macrophages, in a homogeneous differentiation state, using the human monocytic cell line THP-1 previously used to assess immunomodulatory properties of low-molecular-weight allergens, hormones, dietary supplements and therapeutic drugs. RESULTS Zymosan and mushroom polysaccharide extracts lead to a heterogeneous differentiation state of THP-1 monocytes, and these cells secrete low levels of cytokines upon stimulation. Differentiation into macrophages using a low concentration of phorbol 12-myristate 13-acetate improved responsiveness. Elevated levels of cytokines were secreted by cells in a homogenous differentiation state. In addition, it was determined that the assay performs best when using cells at a concentration of (2.5–5)¿×¿105 cells mL-1. CONCLUSION An assay was developed suitable to distinguish the immunomodulatory properties of food compounds in a reproducible manner. It was evaluated using eight mushroom species by measuring the secretion of relevant cytokines TNF-a, IL-1ß, IL-6 and IL-10. © 2014 Society of Chemical Industry
Campylobacter fetus subsp. testudinum subsp. nov., isolated from humans and reptiles
Fitzgerald, C. ; Tu, Z.C. ; Patrick, M. ; Stiles, T. ; Lawson, A.J. ; Santovenia, M. ; Gilbert, M.J. ; Bergen, M. von; Joyce, K. ; Pruckler, J. ; Stroika, S. ; Duim, B. ; Miller, W.G. ; Loparev, V. ; Sinnige, J.C. ; Fields, P.I. ; Tauxe, R.V. ; Blaser, M.J. ; Wagenaar, J.A. - \ 2014
International Journal of Systematic and Evolutionary Microbiology 64 (2014). - ISSN 1466-5026 - p. 2944 - 2948.
genus campylobacter - pcr assay - differentiation - identification - strains - origins
A polyphasic study was undertaken to determine the taxonomic position of 13 Campylobacter fetus-like strains from humans (n=8) and reptiles (n=5). The results of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS and genomic data from sap analysis, 16S rRNA gene and hsp60 sequence comparison, pulsed-field gel electrophoresis, amplified fragment length polymorphism analysis, DNA-DNA hybridization and whole genome sequencing demonstrated that these strains are closely related to C. fetus but clearly differentiated from recognized subspecies of C. fetus. Therefore, this unique cluster of 13 strains represents a novel subspecies within the species C. fetus, for which the name Campylobacter fetus subsp. testudinum subsp. nov. is proposed, with strain 03-427(T) (=ATCC BAA-2539(T)=LMG 27499(T)) as the type strain. Although this novel taxon could not be differentiated from C. fetus subsp. fetus and C. fetus subsp. venerealis using conventional phenotypic tests, MALDI-TOF MS revealed the presence of multiple phenotypic biomarkers which distinguish Campylobacter fetus subsp. testudinum subsp. nov. from recognized subspecies of C. fetus.
Analyses of historical and current populations of black grouse in Central Europe reveal strong effects of genetic drift and loss of genetic diversity
Segelbacher, G. ; Strand, T.M. ; Quintela, M. ; Axelsson, T. ; Jansman, H.A.H. ; Koelewijn, H.P. ; Hoglund, J. - \ 2014
Conservation Genetics 15 (2014)5. - ISSN 1566-0621 - p. 1183 - 1195.
major histocompatibility complex - capercaillie tetrao-urogallus - hamster cricetus-cricetus - balancing selection - allele frequencies - climate-change - mhc - loci - markers - differentiation
Black grouse (Tetrao tetrix) in Central Europe have undergone a severe contraction of their range in recent decades with only a few small isolated remaining populations. Here we compare genetic diversity of two contemporary isolated populations (Sallandse Heuvelrug, Netherlands and Luneburger Heide, Germany) with historical samples from the same region collected within the last one hundred years. We use markers with both putatively neutral and functional variation to test whether the present small and highly fragmented populations hold lower genetic diversity compared to the former larger population. For this we applied three different types of genetic markers: nine microsatellites and 21 single nucleotide polymorphisms (SNPs), both sets which have been found to be neutral, and two functional major histocompatibility complex (MHC) genes for which there is evidence they are under selection. The contemporary small isolated populations displayed lower neutral genetic diversity compared to the corresponding historical samples. Furthermore, samples from Denmark showed that this now extinct population displayed lower genetic variation in the period immediately prior to the local extinction. Population structure was more pronounced among contemporary populations compared to historical populations for microsatellites and SNPs. This effect was not as distinct for MHC which is consistent with the possibility that MHC has been subjected to balancing selection in the past, a process which maintains genetic variation and may minimize population structure for such markers. Genetic differentiation among the present populations highlights the strong effects of population decline on the genetic structure of natural populations, which can be ultimately attributed to habitat loss following anthropogenic land use changes.
Bluetongue virus without NS3/NS3a expression is not virulent and protects against virulent bluetongue virus challenge.
Feenstra, F. ; Gennip, H.G.P. van; Maris-Veldhuis, M.A. ; Verheij, E. ; Rijn, P.A. van - \ 2014
Journal of General Virology 95 (2014)Pt. 9. - ISSN 0022-1317 - p. 2019 - 2029.
vaccinated animals - rna segment - serotype 8 - sheep - antibodies - particles - europe - cattle - ns3 - differentiation
Bluetongue is a disease in ruminants caused by the bluetongue virus (BTV), and is spread by Culicoides biting midges. Bluetongue outbreaks cause huge economic losses and death in sheep in several parts of the world. The most effective measure to control BTV is vaccination. However, both commercially available vaccines and recently developed vaccine candidates have several shortcomings. Therefore, we generated and tested next-generation vaccines for bluetongue based on the backbone of a laboratory-adapted strain of BTV-1, avirulent BTV-6 or virulent BTV-8. All vaccine candidates were serotyped with VP2 of BTV-8 and did not express NS3/NS3a non-structural proteins, due to induced deletions in the NS3/NS3a ORF. Sheep were vaccinated once with one of these vaccine candidates and were challenged with virulent BTV-8 3 weeks after vaccination. The NS3/NS3a knockout mutation caused complete avirulence for all three BTV backbones, including for virulent BTV-8, indicating that safety is associated with the NS3/NS3a knockout phenotype. Viraemia of vaccine virus was not detected using sensitive PCR diagnostics. Apparently, the vaccine viruses replicated only locally, which will minimize spread by the insect vector. In particular, the vaccine based on the BTV-6 backbone protected against disease and prevented viraemia of challenge virus, showing the efficacy of this vaccine candidate. The lack of NS3/NS3a expression potentially enables the differentiation of infected from vaccinated animals, which is important for monitoring virus spread in vaccinated livestock. The disabled infectious single-animal vaccine for bluetongue presented here is very promising and will be the subject of future studies.
Glucose Gradients Influence Zonal Matrix Deposition in 3D Cartilage Constructs
Spitters, T.W. ; Mota, C.M.D. ; Uzoechi, S.C. ; Slowinska, B. ; Martens, D.E. ; Moroni, L. ; Karperien, M. - \ 2014
Tissue Engineering. Part A 20 (2014)23-24. - ISSN 1937-3341 - p. 3270 - 3278.
tissue-engineered cartilage - seeded alginate constructs - articular chondrocytes - oxygen-consumption - gene-expression - culture - hypoxia - differentiation - osteoarthritis - mitochondria
Reproducing the native collagen structure and glycosaminoglycan (GAG) distribution in tissue-engineered cartilage constructs is still a challenge. Articular cartilage has a specific nutrient supply and mechanical environment due to its location and function in the body. Efforts to simulate this native environment have been reported through the use of bioreactor systems. However, few of these devices take into account the existence of gradients over cartilage as a consequence of the nutrient supply by diffusion. We hypothesized that culturing chondrocytes in an environment, in which gradients of nutrients can be mimicked, would induce zonal differentiation. Indeed, we show that glucose gradients facilitating a concentration distribution as low as physiological glucose levels enhanced a zonal chondrogenic capacity similar to the one found in native cartilage. Furthermore, we found that the glucose consumption rates of cultured chondrocytes were higher under physiological glucose concentrations and that GAG production rates were highest in 5mM glucose. From these findings, we concluded that this condition is better suited for matrix deposition compared to 20mM glucose standard used in a chondrocyte culture system. Reconsidering the culture conditions in cartilage tissue engineering strategies can lead to cartilaginous constructs that have better mechanical and structural properties, thus holding the potential of further enhancing integration with the host tissue.
WOX5 Suppresses CYCLIN D Activity to Establish Quiescence at the Center of the Root Stem Cell Niche
Forzani, C. ; Aichinger, E. ; Willemsen, V. ; Murray, J.A. - \ 2014
Current Biology 24 (2014)16. - ISSN 0960-9822 - p. 1939 - 1944.
arabidopsis-thaliana root - division - meristem - differentiation - organization - transition - expression - complex - protein
In Arabidopsis, stem cells maintain the provision of new cells for root growth. They surround a group of slowly dividing cells named the quiescent center (QC), and, together, they form the stem cell niche (SCN). The QC acts as the signaling center of the SCN, repressing differentiation of the surrounding stem cells [1] and providing a pool of cells able to replace damaged stem cells [2, 3]. Maintenance of the stem cells depends on the transcription factor WUSCHEL-RELATED HOMEOBOX 5 (WOX5), which is specifically expressed in the QC [4]. However, the molecular mechanisms by which WOX5 promotes stem cell fate and whether WOX5 regulates proliferation of the QC are unknown. Here, we reveal a new role for WOX5 in restraining cell division in the cells of the QC, thereby establishing quiescence. In contrast, WOX5 and CYCD3;3/CYCD1;1 both promote cell proliferation in the nascent columella. The additional QC divisions occurring in wox5 mutants are suppressed in mutant combinations with the D type cyclins CYCD3;3 and CYCD1;1. Moreover, ectopic expression of CYCD3;3 in the QC is sufficient to induce cell division in the QC. WOX5 thus suppresses QC divisions that are otherwise promoted by CYCD3;3 and CYCD1;1, in part by interacting with the CYCD3;3 promoter to repress CYCD3;3 expression in the QC. Therefore, we propose a specific role for WOX5 in initiating and maintaining quiescence of the QC by excluding CYCD activity from the QC.
Precise control of plant stem cell activity through parallel regulatory inputs
Bennett, T. ; Toorn, A. van; Willemsen, V. ; Scheres, B. - \ 2014
Development 141 (2014). - ISSN 0950-1991 - p. 4055 - 4064.
arabidopsis-thaliana root - transcription factor - shoot apex - meristem - gene - differentiation - organization - maintenance - homeostasis - sombrero
The regulation of columella stem cell activity in the Arabidopsis root cap by a nearby organizing centre, the quiescent centre, has been a key example of the stem cell niche paradigm in plants. Here, we investigate interactions between transcription factors that have been shown to regulate columella stem cells using a simple quantification method for stem cell activity in the root cap. Genetic and expression analyses reveal that the RETINOBLASTOMA-RELATED protein, the FEZ and SOMBRERO NAC-domain transcription factors, the ARF10 and ARF16 auxin response factors and the quiescent centre-expressed WOX5 homeodomain protein each provide independent inputs to regulate the number of columella stem cells. Given the tight control of columella development, we found that these inputs act in a surprisingly parallel manner. Nevertheless, important points of interaction exist; for example, we demonstrate the repression of SMB activity by non-autonomous action of WOX5. Our results suggest that the developmental progression of columella stem cells may be quantitatively regulated by several more broadly acting transcription factors rather than by a single intrinsic stem cell factor, which raises questions about the special nature of the stem cell state in plants.
Irreversible fate commitment in the Arabidopsis stomatal lineage requires a Fama and Retinoblastoma-related module
Matos, J.L. ; Lau, O.S. ; Hachez, C. ; Cruz-Ramirez, A. ; Scheres, B. ; Bergmann, D.C. - \ 2014
eLife 3 (2014). - ISSN 2050-084X
asymmetric cell divisions - gateway binary vectors - transcription factor - secretory peptide - guard-cells - differentiation - expression - genes - transformation - termination
The presumed totipotency of plant cells leads to questions about how specific stem cell lineages and terminal fates could be established. In the Arabidopsis stomatal lineage, a transient self-renewing phase creates precursors that differentiate into one of two epidermal cell types, guard cells or pavement cells. We found that irreversible differentiation of guard cells involves RETINOBLASTOMA-RELATED (RBR) recruitment to regulatory regions of master regulators of stomatal initiation, facilitated through interaction with a terminal stomatal lineage transcription factor, FAMA. Disrupting physical interactions between FAMA and RBR preferentially reveals the role of RBR in enforcing fate commitment over its role in cell-cycle control in this developmental context. Analysis of the phenotypes linked to the modulation of FAMA and RBR sheds new light on the way iterative divisions and terminal differentiation are coordinately regulated in a plant stem-cell lineage. - See more at: http://elifesciences.org/content/3/e03271#sthash.f3srCCrx.dpuf
Development of a pluripotent stem cell derived neuronal model to identify chemically induced pathway perturbation in relation to neurotoxicity: effects of CREB pathway inhibition
Pistollato, F. ; Louisse, J. ; Scelfo, B. ; Mennecozzi, M. ; Accordi, B. ; Basso, B. ; Gaspar, J.A. ; Zagoura, D. ; Barilari, M. ; Palosaari, T. ; Sachinidis, A. ; Bremer, S. - \ 2014
Toxicology and Applied Pharmacology 280 (2014)2. - ISSN 0041-008X - p. 378 - 388.
c-fos - in-vitro - response element - x-inactivation - mechanisms - expression - toxicity - differentiation - identification - contributes
According to the advocated paradigm shift in toxicology, acquisition of knowledge on the mechanisms underlying the toxicity of chemicals, such as perturbations of biological pathways, is of primary interest. Pluripotent stem cells (PSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer a unique opportunity to derive physiologically relevant human cell types to measure molecular and cellular effects of such pathway modulations. Here we compared the neuronal differentiation propensity of hESCs and hiPSCs with the aim to develop novel hiPSC-based tools for measuring pathway perturbation in relation to molecular and cellular effects in vitro. Among other fundamental pathways, also, the cAMP responsive element binding protein (CREB) pathway was activated in our neuronal models and gave us the opportunity to study time-dependent effects elicited by chemical perturbations of the CREB pathway in relation to cellular effects. We show that the inhibition of the CREB pathway, using 2-naphthol-AS-E-phosphate (KG-501), induced an inhibition of neurite outgrowth and synaptogenesis, as well as a decrease of MAP2+ neuronal cells. These data indicate that a CREB pathway inhibition can be related to molecular and cellular effects that may be relevant for neurotoxicity testing, and, thus, qualify the use of our hiPSC-derived neuronal model for studying chemical-induced neurotoxicity resulting from pathway perturbations.
Uitwerking interview workshop Onderscheid in Vers : Gerben Splinter in gesprek met drie deelnemers van het project PPP Paprika
Splinter, Gerben - \ 2014
horticulture - sweet peppers - program evaluation - sales promotion - consumer economics - cooperation - taste - merchandise information - knowledge - differentiation - varieties
Genetic divergence and evidence for sympatric host-races in the highly polyphagous brown tail moth, Euproctis chrysorrhoea (Lepidoptera: Erebidae)
Marques, J.F. ; Wang, H.L. ; Svensson, G.P. ; Frago Clols, E. ; Anderbrant, O. - \ 2014
Evolutionary Ecology 28 (2014)5. - ISSN 0269-7653 - p. 829 - 848.
plant-feeding insects - tree arbutus-unedo - evolutionary history - mitochondrial - populations - speciation - refugia - time - diversification - differentiation
The brown tail moth (BTM) Euproctis chrysorrhoea (Linnaeus 1758) (Lepidoptera: Erebidae) is a forest and ornamental pest in Europe and the United States. Its extreme polyphagy, and documented phenological shift associated with host use suggest the presence of distinct host-races. To test this hypothesis, we sampled BTM infesting different host species in several locations along its distribution, and used DNA sequence data (a total of 1,672 bp from cytochrome c oxidase subunit I, elongation factor 1-alpha, and wingless) to produce haplotype networks and reconstruct the phylogenetic relationships between individuals. Population genetic diversity indices pointed out a higher genetic diversity in Europe, particularly in the samples from southern Spain and southern England. Lower F ST values were found between geographically closer populations when compared to more distant ones, but analyses of molecular variance and Mantel tests failed to reveal geographically associated genetic differentiation. However, haplotype networks and phylogenetic reconstructions revealed a previously unknown genetic differentiation within the BTM, with one lineage circumscribed to southern Europe. Although BTM haplotypes did not cluster according to their host plant, host-associated haplotypes were observed within certain geographic regions. Hence, our data support the existence of host-races of BTM within southern Spain and southern England, where populations from different hosts occur in sympatry.
Time course and role of luteinizing hormone and follicle-stimulating hormone in the expansion of the Leydig cell population at the time of puberty in the rhesus monkey (Macaca mulatta)
Verhagen, I. ; Ramaswamy, S. ; Teerds, K.J. ; Keijer, J. ; Plant, T.M. - \ 2014
Andrology 2 (2014)6. - ISSN 2047-2927 - p. 924 - 930.
gonadotropin-secretion - postnatal-development - human testis - proliferation - testosterone - fsh - differentiation - fascicularis - spermatogonia - localization
In higher primates, development of the adult population of Leydig cells has received little attention. Here, the emergence of 3beta-hydroxysteroid dehydrogenase (HSD3B) positive cells in the testis of the rhesus monkey was examined during spontaneous puberty, and correlated with S-phase labeling in the interstitium at this critical stage of development. In addition, the relative role of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in initiating the pubertal expansion of Leydig cells was studied by precociously stimulating the juvenile testis in vivo with pulsatile 11-day infusions of recombinant LH and FSH, either alone or in combination. At the time of castration, testes were immersion fixed in Bouin's, embedded in paraffin, and sectioned at 5mum. Leydig cells/testis were enumerated using HSD3B as a Leydig cell marker. Leydig cell number per testis increased progressively during puberty to reach values in the adult approximately 10 fold greater than in early-pubertal animals. The rise in cell number was associated with an increase in nuclear diameter. That the pubertal expansion of Leydig cell number was driven primarily by the increase in LH secretion at this stage of development was suggested by the finding that precocious stimulation of mid-juvenile monkeys with LH, either alone or in combination with that of FSH, resulted in a 20-30 fold increase in the number of HSD3B-positive cells. Interestingly, precocious FSH stimulation, alone, also resulted in appearance of Leydig cells as indicated by the occasional HSD3B-positive cell in the interstitium. The nuclear diameter of these Leydig cells, however, was less than that of those generated in response to LH.
Quantification of variability in trichome patterns
Greese, B. ; Huelskamp, M. ; Fleck, C. - \ 2014
Frontiers in Plant Science 5 (2014). - ISSN 1664-462X
reaction-diffusion systems - to-cell variability - gene-expression - spatial-pattern - biological-systems - lateral inhibition - voronoi diagrams - differentiation - arabidopsis - mechanism
While pattern formation is studied in various areas of biology, little is known about the intrinsic noise leading to variations between individual realizations of the pattern. One prominent example for de novo pattern formation in plants is the patterning of trichomes on Arabidopsis leaves, which involves genetic regulation and cell-to-cell communication. These processes are potentially variable due to , e.g., the abundance of cell components or environmental conditions. To elevate the understanding of the regulatory processes underlying the pattern formation it is crucial to quantitatively analyze the variability in naturally occurring patterns. Here, we review recent approaches towards characterization of noise on trichome initiation. We present methods for the quantification of spatial patterns, which are the basis for data-driven mathematical modeling and enable the analysis of noise from different sources. Besides the insight gained on trichome formation, the examination of observed trichome patterns also shows that highly regulated biological processes can be substantially affected by variability.
Fate map of Medicago truncatula root nodules
Xiao, T.T. ; Schilderink, S. ; Moling, S. ; Deinum, E.E. ; Kondorosi, E. ; Franssen, H. ; Kulikova, O. ; Niebel, A. ; Bisseling, T. - \ 2014
Development 141 (2014). - ISSN 0950-1991 - p. 3517 - 3528.
rhizobial infection - cortical-cells - nod factors - arabidopsis - differentiation - protein - expression - initiation - activator - symbiosis
Legume root nodules are induced by N-fixing rhizobium bacteria that are hosted in an intracellular manner. These nodules are formed by reprogramming differentiated root cells. The model legume Medicago truncatula forms indeterminate nodules with a meristem at their apex. This organ grows by the activity of the meristem that adds cells to the different nodule tissues. In Medicago sativa it has been shown that the nodule meristem is derived from the root middle cortex. During nodule initiation, inner cortical cells and pericycle cells are also mitotically activated. However, whether and how these cells contribute to the mature nodule has not been studied. Here, we produce a nodule fate map that precisely describes the origin of the different nodule tissues based on sequential longitudinal sections and on the use of marker genes that allow the distinction of cells originating from different root tissues. We show that nodule meristem originates from the third cortical layer, while several cell layers of the base of the nodule are directly formed from cells of the inner cortical layers, root endodermis and pericycle. The latter two differentiate into the uninfected tissues that are located at the base of the mature nodule, whereas the cells derived from the inner cortical cell layers form about eight cell layers of infected cells. This nodule fate map has then been used to re-analyse several mutant nodule phenotypes. This showed, among other things, that intracellular release of rhizobia in primordium cells and meristem daughter cells are regulated in a different manner.
Eicosapentaenoic acid free fatty acid prevents and suppresses colonic neoplasia in colitis-associated colorectal cancer acting on Notch signaling and gut microbiota
Piazzi, G. ; Argenio, G. D'; Prossomariti, A. ; Lembo, V. ; Mazzone, G. ; Candela, M. ; Biagi, E. ; Brigidi, P. ; Vitaglione, P. ; Fogliano, V. ; Angelo and others, L. D' - \ 2014
International Journal of Cancer 135 (2014)9. - ISSN 0020-7136 - p. 2004 - 2013.
inflammatory-bowel-disease - dietary fish-oil - intestinal microbiota - mouse model - docosahexaenoic acid - mice - sodium - cells - differentiation - chemoprevention
Inflammatory bowel diseases are associated with increased risk of developing colitis-associated colorectal cancer (CAC). Epidemiological data show that the consumption of ¿-3 polyunsaturated fatty acids (¿-3 PUFAs) decreases the risk of sporadic colorectal cancer (CRC). Importantly, recent data have shown that eicosapentaenoic acid-free fatty acid (EPA-FFA) reduces polyp formation and growth in models of familial adenomatous polyposis. However, the effects of dietary EPA-FFA are unknown in CAC. We tested the effectiveness of substituting EPA-FFA, for other dietary fats, in preventing inflammation and cancer in the AOM-DSS model of CAC. The AOM-DSS protocols were designed to evaluate the effect of EPA-FFA on both initiation and promotion of carcinogenesis. We found that EPA-FFA diet strongly decreased tumor multiplicity, incidence and maximum tumor size in the promotion and initiation arms. Moreover EPA–FFA, in particular in the initiation arm, led to reduced cell proliferation and nuclear ß-catenin expression, whilst it increased apoptosis. In both arms, EPA-FFA treatment led to increased membrane switch from ¿-6 to ¿-3 PUFAs and a concomitant reduction in PGE2 production. We observed no significant changes in intestinal inflammation between EPA-FFA treated arms and AOM-DSS controls. Importantly, we found that EPA-FFA treatment restored the loss of Notch signaling found in the AOM-DSS control and resulted in the enrichment of Lactobacillus species in the gut microbiota. Taken together, our data suggest that EPA-FFA is an excellent candidate for CRC chemoprevention in CAC.
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