The distribution of lectins across the phylum Nematoda : a genome-wide search

Nematodes are a very diverse phylum that has adapted to nearly every ecosystem. They have developed specialized lifestyles, dividing the phylum into free-living, animal, and plant parasitic species. Their sheer abundance in numbers and presence in nearly every ecosystem make them the most prevalent animals on earth. In this research nematode-specific profiles were designed to retrieve predicted lectin-like domains from the sequence data of nematode genomes and transcriptomes. Lectins are carbohydrate-binding proteins that play numerous roles inside and outside the cell depending on their sugar specificity and associated protein domains. The sugar-binding properties of the retrieved lectin-like proteins were predicted in silico. Although most research has focused on C-type lectin-like, galectin-like, and calreticulin-like proteins in nematodes, we show that the lectin-like repertoire in nematodes is far more diverse. We focused on C-type lectins, which are abundantly present in all investigated nematode species, but seem to be far more abundant in free-living species. Although C-type lectin-like proteins are omnipresent in nematodes, we have shown that only a small part possesses the residues that are thought to be essential for carbohydrate binding. Curiously, hevein, a typical plant lectin domain not reported in animals before, was found in some nematode species

Horizontal gene transfer contributes to plant evolution : the case of Agrobacterium T-DNAs

Horizontal gene transfer (HGT) can be defined as the acquisition of genetic material from another organism without being its offspring. HGT is common in the microbial world including archaea and bacteria, where HGT mechanisms are widely understood and recognized as an important force in evolution. In eukaryotes, HGT now appears to occur more frequently than originally thought. Many studies are currently detecting novel HGT events among distinct lineages using next-generation sequencing. Most examples to date include gene transfers from bacterial donors to recipient organisms including fungi, plants, and animals. In plants, one well-studied example of HGT is the transfer of the tumor-inducing genes (T-DNAs) from some Agrobacterium species into their host plant genomes. Evidence of T-DNAs from Agrobacterium spp. into plant genomes, and their subsequent maintenance in the germline, has been reported in Nicotiana, Linaria and, more recently, in Ipomoea species. The transferred genes do not produce the usual disease phenotype, and appear to have a role in evolution of these plants. In this paper, we review previous reported cases of HGT from Agrobacterium, including the transfer of T-DNA regions from Agrobacterium spp. to the sweetpotato [ Ipomoea batatas (L.) Lam.] genome which is, to date, the sole documented example of a naturally-occurring incidence of HGT from Agrobacterium to a domesticated crop plant. We also discuss the possible evolutionary impact of T-DNA acquisition on plants

Sensitivity towards DMI fungicides and haplotypic diversity of their CYP51 target in the Mycosphaerella graminicola population of Flanders

Septoria leaf blotch, caused by the fungus Mycosphaerella graminicola, is the most important wheat disease in Northwestern Europe, and is currently controlled by fungicide applications. Since the spread of resistance to methyl benzimidazole carbamates (MBCs) and quinone outside inhibitors (QoIs) in European countries, reliable control is mainly dependent upon sterol 14 alpha-demethylation inhibitors (DMIs). In the last decades however, a slow shift towards reduced sensitivity of M. graminicola to DMIs has been observed. This shift is caused mainly by mutations in the CYP51 gene encoding the 14 alpha-demethylase target protein for these fungicides. In this work, M. graminicola isolates were sampled at fields spread over Flanders, Belgium. In vitro assays were used to analyze the sensitivity of the Flemish M. graminicola population towards different DMIs. Sequencing of the CYP51 gene of these isolates allowed us to identify and map the haplotypes in this population. The results showed that there is a large variability in DMI sensitivity between the isolates, even within one field, which is reflected in a high diversity in CYP51 haplotypes within the M. graminicola population in Flanders. Next to some haplotypes that were not described in literature before, we found that the population is dominated by CYP51 haplotypes which were previously associated with increased resistance towards DMIs

Biochar-amended potting medium reduces the susceptibility of rice to root-knot nematode infections

Background: Biochar is a solid coproduct of biomass pyrolysis, and soil amended with biochar has been shown to enhance the productivity of various crops and induce systemic plant resistance to fungal pathogens. The aim of this study was to explore the ability of wood biochar to induce resistance to the root-knot nematode (RKN) Meloidogyne graminicola in rice (Oryza sativa cv. Nipponbare) and examine its histochemical and molecular impact on plant defense mechanisms. Results: A 1.2 % concentration of biochar added to the potting medium of rice was found to be the most effective at reducing nematode development in rice roots, whereas direct toxic effects of biochar exudates on nematode viability, infectivity or development were not observed. The increased plant resistance was associated with biochar-primed H2O2 accumulation as well as with the transcriptional enhancement of genes involved in the ethylene (ET) signaling pathway. The increased susceptibility of the Ein2b-RNAi line, which is deficient in ET signaling, further confirmed that biochar-induced priming acts at least partly through ET signaling. Conclusion: These results suggest that biochar amendments protect rice plants challenged by nematodes. This priming effect partially depends on the ET signaling pathway and enhanced H2O2 accumulation

Interplay between carotenoids, abscisic acid and jasmonate guides the compatible rice-Meloidogyne graminicola interaction

In this study, we have characterized the role of carotenoids and chlorophyll in the compatible interaction between the sedentary root knot nematode (RKN) Meloidogyne graminicola and the monocot model plant rice (Oryza sativa). Previous transcriptome data showed a differential expression of carotenoid and chlorophyll biosynthesis genes in nematode-induced giant cells and gall tissue. Metabolite measurement showed that galls indeed accumulate chlorophyll a, b and carotenoids, as well as the hormone abscisic acid (ABA). When ABA was externally applied on rice plants, or when ABA-biosynthesis was inhibited, a significant increase in gall formation and nematode development was found, showing the complex role of ABA in this interaction. ABA application suppressed jasmonic acid (JA) levels in the plants, while ABA-biosynthesis inhibition lead to increased JA levels confirming an antagonism between ABA and JA in rice roots. In addition, combined applications of ABA and JA showed that the ABA-effect can overcome JA-induced defense. Based on these observations, we hypothesized that the accumulation of chlorophyll and carotenoid precursors would be beneficial to nematode infection. Indeed, when chemically blocking the carotenoid biosynthesis pathway at different steps, which leads to differential accumulation of carotenoids and chlorophyll in the plants, a positive and clear link between accumulation of carotenoids and chlorophyll and rice susceptibility to RKN was detected

Change in the Dispersed Territory: (Proto)Types for a New Urban Paradigm

Dispersed territories such as Flanders (Belgium) have been amongst others described as layered territories, as a palimpsest landscape, or as both a selective and a-selective infill of the territory. In the constant re-editing and change of this territory, historical remnants remain visible and often form a departing point for further adaptations and changes. One of these remnants, the moated farmstead, has evolved from a historical (proto)type to a common typology in South-West Flanders and enabled inhabiting the territory dispersedly. Moated farmsteads are typically composed of a series of different buildings and are surrounded by an artificial water body. The moat formed the central point of a larger land management system. Nowadays, many of these farmsteads still exist, however, over time they lost their original purpose and transformed into a variety of uses. The design of a prototype, i.e., a first model later evolving into a type, a recurring model, as an architectural object can simultaneously relate to a larger theoretical reflection on the scale of the territory. Subsequently, these farmsteads lead to the question: What (proto)types have been developed to demonstrate the uniqueness of the relation between the land/labour/living in a dispersed territory? Can we re-interpret the moated farmstead as a new (proto)type to establish a more sustainable way of urbanising the countryside in a dispersed context? Therefore, this article first documents the historical figure of the moated farmstead as an architectural object, socio-economic and political organisation, and ecological land management, and documents its change throughout time. Then, a reflection is built on how, at the time of their emergence, these moated farmsteads were an exponent of a sustainable and ground-breaking type that enabled a dispersed settlement pattern. Finally, the potential of the farmstead as a new prototype for a twenty-first-century dispersed territory is discussed

Energy-Momentum Distribution: Some Examples

In this paper, we elaborate the problem of energy-momentum in General Relativity with the help of some well-known solutions. In this connection, we use the prescriptions of Einstein, Landau-Lifshitz, Papapetrou and M\"{o}ller to compute the energy-momentum densities for four exact solutions of the Einstein field equations. We take the gravitational waves, special class of Ferrari-Ibanez degenerate solution, Senovilla-Vera dust solution and Wainwright-Marshman solution. It turns out that these prescriptions do provide consistent results for special class of Ferrari-Ibanez degenerate solution and Wainwright-Marshman solution but inconsistent results for gravitational waves and Senovilla-Vera dust solution.Comment: 20 pages, accepted for publication in Int. J. Mod. Phys.

The moderating effect of psychosocial factors in the relation between neighborhood walkability and children’s physical activity

BACKGROUND: The study aimed to investigate if psychosocial factors moderate the association between objective walkability and different domains of children's physical activity (PA). A second aim of the study was to investigate the direct associations between psychosocial factors and children's PA. Based on previous literature, it was hypothesized that walkability would be more strongly related to PA among children with negative psychosocial profiles. METHODS: Data were collected between December 2011 and May 2013 as part of the Belgian Environmental Physical Activity Study in children (BEPAS-child). In total, data from 494 children and one of their parents were included in the study. Children wore an accelerometer for 7 consecutive days and together with one of their parents, they completed the Flemish Physical Activity Questionnaire. Parents filled out a questionnaire concerning their child's psychosocial factors toward PA (i.e. parental attitude toward their child's PA, parental social norm toward their child's PA, parental support, friend support, children's self-efficacy, and perceived benefits and barriers toward sports and PA). Neighborhood walkability was calculated using geographical information systems (GIS). Multilevel cross-classified analyses were conducted. RESULTS: Of the 42 investigated interactions between neighborhood walkability and psychosocial factors in relation to PA among children, only 7 significant interactions were found of which 3 were only significant among children from low-income neighborhoods. Parental support and self-efficacy were positive correlates of children's PA in high- and low-income neighborhoods independent of the level of walkability, but effect sizes were small. CONCLUSIONS: The hypothesis that walkability would be more strongly related to PA among children with negative psychosocial profiles could not be confirmed and in general, psychosocial factors and objective walkability did not interact in relation to children's PA. Focusing on parental support and self-efficacy towards PA can possibly cause small effects on children's PA in both high- and low-walkable neighborhoods, as well as in high- and low-income neighborhoods