A lectin isolated from the roots of the legume, Dolichos biflorus, binds to Nod factors produced by rhizobial strains that nodulate this plant and has a deduced amino acid sequence with no significant homology to any lectin reported to date. This lectin also is an enzyme that catalyzes the hydrolysis of phosphoanhydride bonds of nucleoside di-and triphosphates; the enzyme activity is increased in the presence of carbohydrate ligands. This lectin-nucleotide phosphohydrolase (LNP) has a substrate specificity characteristic of the apyrase category of phosphohydrolases, and its sequence contains four motifs characteristic of this category of enzymes. LNP is present on the surface of the root hairs, and treatment of roots with antiserum to LNP inhibits their ability to undergo root hair deformation and to form nodules on exposure to rhizobia. These properties suggest that this protein may play a role in the rhizobium-legume symbiosis and/or in a related carbohydrate recognition event endogenous to the plant.Oligosaccharide signaling events play important roles in the regulation of plant development, defense, and other interactions of plants with the environment (1-4). The establishment of the nitrogen-fixing symbiotic relationship between rhizobia and leguminous plants depends on such a signaling process. The rhizobia produce lipochitooligosaccharidic signals, called Nod factors, that elicit the differentiation of a new organ, the nodule, in the root cortex. The rhizobia bind to and invade the root hairs, where they proceed to the emerging nodule within infection threads produced by the plant (5). Both the initiation of nodule formation and rhizobial entry are host-strainspecific; this specificity is determined by the type of Nod factor produced by a particular rhizobial strain and by the ability of a leguminous species to recognize that signal.All Nod factors consist of a short, typically tetrapentameric, chitin oligosaccharidic backbone that is N-acylated at the nonreducing end, usually with a common fatty acid, such as cis-vaccenic acid. The Nod factors differ from one another in length of this backbone and the type of substituents that decorate it; these modifications determine the strain specificity of the rhizobium and depend on the set of nodulation genes possessed by that rhizobial strain (4). A related set of signals are the chitin oligosaccharides, themselves, that have been found to elicit defense responses in a wide variety of plants (for review, see ref.3).Although the structures of many of these chitooligosaccharides have been characterized, little is known about the plant proteins that bind these signals, whether as receptors for signal transduction or as binding proteins with other functions. High-affinity binding sites for chitin fragments have been found on membranous fractions prepared from tomato (7) and rice (8) suspension-cultured cells, and a 70-kDa protein that binds to chitin fragments was isolated from the rice membranes (9). Particulate fractions from roots of the legume, Medicago t...
Human hair dermal papilla (DP) cells are specialized mesenchymal cells that play a pivotal role in hair regeneration and hair cycle activation. The current study aimed to first develop three-dimensional (3D) DP spheroids (DPS) with or without a silk-gelatin (SG) microenvironment, which showed enhanced DP-specific gene expression, resulting in enhanced extracellular matrix (ECM) production compared with a monolayer culture. We tested the feasibility of using this DPS model for drug screening by using minoxidil, which is a standard drug for androgenic alopecia. Minoxidil-treated DPS showed enhanced expression of growth factors and ECM proteins. Further, an attempt has been made to establish an in vitro 3D organoid model consisting of DPS encapsulated by SG hydrogel and hair follicle (HF) keratinocytes and stem cells. This HF organoid model showed the importance of structural features, cell-cell interaction, and hypoxia akin to in vivo HF. The study helped to elucidate the molecular mechanisms to stimulate cell proliferation, cell viability, and elevated expression of HF markers as well as epithelial-mesenchymal crosstalks, demonstrating high relevance to human HF biology. This simple in vitro DP organoid model system has the potential to provide significant insights into the underlying mechanisms of HF morphogenesis, distinct molecular signals relevant to different stages of the hair cycle, and hence can be used for controlled evaluation of the efficacy of new drug molecules.
The roots of the legume Dolichos biflorus contain a lectin/nucleotide phosphohydrolase (Db-LNP) that binds to the Nod factor signals produced by rhizobia that nodulate this plant. In this study we show that Db-LNP is differentially distributed along the surface of the root axis in a pattern that correlates with the zone of nodulation of the root. Db-LNP is present on the surface of young and emerging root hairs and redistributes to the tips of the root hairs in response to treatment of the roots with a rhizobial symbiont or with a carbohydrate ligand. This redistribution does not occur in response to a non-symbiotic rhizobial strain or a root pathogen. Db-LNP is also present in the root pericycle where its level decreases upon initiation of nodule formation. Maximum levels of Db-LNP are found in 2-d-old roots, and the expression of this root protein is increased when the plants are grown in the absence of NO 3 Ϫ and NH 4 ϩ . These results support the possibility that Db-LNP is involved in the initiation of the Rhizobium legume symbiosis.
(J.S., P.M.G.)Nodulation in legumes requires the recognition of rhizobially made Nod factors. Genetic studies have revealed that the perception of Nod factors involves LysM domain receptor-like kinases, while biochemical approaches have identified LECTIN NUCLEOTIDE PHOSPHOHYDROLASE (LNP) as a Nod factor-binding protein. Here, we show that antisense inhibition of LNP blocks nodulation in Lotus japonicus. This absence of nodulation was due to a defect in Nod factor signaling based on the observations that the early nodulation gene NODULE INCEPTION was not induced and that both Nod factor-induced perinuclear calcium spiking and calcium influx at the root hair tip were blocked. However, Nod factor did induce root hair deformation in the LNP antisense lines. LNP is also required for infection by the mycorrhizal fungus Glomus intraradices, suggesting that LNP plays a role in the common signaling pathway shared by the rhizobial and mycorrhizal symbioses. Taken together, these observations indicate that LNP acts at a novel position in the early stages of symbiosis signaling. We propose that LNP functions at the earliest stage of the common nodulation and mycorrhization symbiosis signaling pathway downstream of the Nod factor receptors; it may act either by influencing signaling via changes in external nucleotides or in conjunction with the LysM receptor-like kinases for recognition of Nod factor.
The glucose-specific peanut root lectin, PRA II, is localized on the surface of 7-day-old peanut seedling root and in root cortical parenchymatous cells. The lectin is eluted from intact roots upon washing with buffer containing glucose. Rabbit erythrocytes bind to the root surface and the cortical cells; the binding is inhibited by antibodies raised against PRA II, peanut-specific Rhizobium cells and by glucose. Lipopolysaccharides isolated from host-specific Rhizobium strain inhibit the haemagglutinating activity of PRA II and are precipitated by the lectin. Our results suggest that PRA II might be involved in recognition of Rhizobium by peanut roots.
Purpose Gut health has multidimensional impact on childhood growth and development. Diet being the major modulator of gut health, this study aims to hypothesize if supplementation of dietary prebiotics and vitamins can impact gut environment of healthy children. Design/methodology/approach A double-blind placebo-controlled trial was conducted with parallel allocation of children 8–13 years of age to placebo or test group. Test group was supplemented with 1.5 g of formulation comprising prebiotics and vitamins, and to placebo, maltodextrin (1.5 g) was supplemented. After four weeks, the effect on markers of gut health (i.e. beneficial microbes, and gut integrity markers such as secretory Immunoglobulin A [sIgA] and calprotectin concentration) was evaluated in feces of children. Findings Significant increase of 17.1% in fecal bifidobacteria counts (p = 0.04) was observed in the test group compared to placebo after four weeks. Also, fecal calprotectin concentration decreased (20%) significantly (p = 0.01) in test group compared to placebo. In addition, the test group showed significant improvement in fecal sIgA and lactobacilli compared to baseline concentration (p = 0.01 and 0.001, respectively). Research limitations/implications This study demonstrates that prebiotic (and vitamin) intervention may influence health outcomes in children by positively modulating markers of gut health. Originality/value There are limited studies demonstrating the efficacy of prebiotic and vitamins on gut health of school age children.
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