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At least 415 records · Page 23Linked to original sources
PubMed2001

DNA synthesis and fragmentation in bacteroids during Astragalus sinicus root nodule development.

Histo- and cytochemical techniques were used to study the DNA replication and fragmentation patterns in bacteroids formed by Mesorhizobium huakuii subsp. rengei in nodules of Astragalus sinicus. DNA replication was detected by the incorporation of 5-bromo deoxy-uridine. Signals denoting DNA synthesis were observed in plant nuclei within the nodule meristem and in bacteroids near the meristem. The TUNEL (TdT-mediated dUTP nick-end labeling) assay was used to measure DNA fragmentation. In nutrient-depleted 1-mpi (month(s) post inoculation) nodule sections, some bacteroids were in vacuoles, and DNA fragmentation signals were observed only in such bacteroids. In contrast, 1-mpi nodule sections without nutrient depletion showed neither bacteroid localization in vacuoles nor DNA fragmentation signals. The bacteroid translocation into vacuoles upon nutrient starvation might results from autophagy of the plant. In 2-mpi nodule sections, bacteroids with DNA fragmentation signals appeared within the cytoplasm of some nodule cells in the senescence zone.

DNA Fragmentation↗
PubMed1996

Use of a subtractive hybridization approach to identify new Medicago truncatula genes induced during root nodule development.

We report the identification of new molecular markers associated with different stages of Rhizobium-induced nodule development in the legume Medicago truncatula. A cDNA library was constructed from pre-nitrogen-fixing M. Truncatula nodules, and differentially screened with a polymerase chain reaction-amplified subtracted probe. Twenty-nine new families of nodulin cDNA clones, designated MtN1 to MtN29, were thus identified in addition to clones for several known nodulins. All MtN genes were shown by Northern (RNA) hybridization analysis to be induced during nodulation, some of them well before nodule emergence. The MtN genes were classified into three groups depending on their expression kinetics. The expression of three MtN genes showed a limited induction by Nod factors purified from Rhizobium meliloti. Homologies with a variety of proteins were found for the deduced amino acid sequences of 10 of the MtN genes.

Amino Acid Sequence↗
PubMed1999

Neurogenin1 and neurogenin2 control two distinct waves of neurogenesis in developing dorsal root ganglia.

Different classes of sensory neurons in dorsal root ganglia (DRG) are generated in two waves: large-diameter trkC+ and trkB+ neurons are born first, followed by small-diameter trkA+ neurons. All such neurons require either neurogenin (ngn) 1 or 2, two neuronal determination genes encoding basic helix-loop-helix (bHLH) transcription factors. ngn2 is required primarily if not exclusively for the generation of trkC+ and trkB+ neurons, whereas the generation of most or all trkA+ neurons requires ngn1. Comparison with previous lineage tracing data in the chick suggests that this dichotomy reflects a requirement for the two ngns in distinct sensory precursor populations. The neurogenesis defect in ngn2(-/-) embryos is transient and later compensated by ngn1-dependent precursors, suggesting that feedback or competitive interactions between these precursors may control the proportion of different neuronal subtypes they normally produce. These data reveal remarkable parallels in the roles of bHLH factors during neurogenesis in the DRG, and myogenesis in the neighboring myotome.

Animals↗
PubMed2003

Systemic inhibition of arbuscular mycorrhiza development by root exudates of cucumber plants colonized by Glomus mosseae.

The arbuscular mycorrhizal (AM) non-host plants mustard, sugar beet, lupin and the AM host plant cucumber were used as test plants. Cucumber plants were grown either in the absence of the AM fungus (AMF) Glomus mosseae or in a split-root system, with one side mycorrhizal and one side non-mycorrhizal. Root exudates of the AM non-host plants, the non-mycorrhizal cucumber plants and the mycorrhizal and the non-mycorrhizal side of the split-root system of mycorrhizal cucumber plants were collected and applied to cucumber plants inoculated with the AMF. Root exudates of non-mycorrhizal cucumber plants showed a significant stimulatory effect on root colonization, whereas root exudates from the mycorrhizal and the non-mycorrhizal sides of a split-root system of a mycorrhizal cucumber plant did not show this stimulatory effect and were even slightly inhibitory. Root exudates of the two AM non-host plants mustard and sugar beet significantly reduced root colonization in cucumber plants, whereas no such effect was observed when root exudates of the AM non-host plant lupin were applied.

Beta vulgaris↗
PubMed2004

Plant development: slowing root growth naturally.

What determines organ size? A screen for plant strains showing natural variation in root length has identified a novel gene that modulates root growth rate by controlling cell division and elongation at the root tip.

Arabidopsis↗
PubMed2000

Taenia solium disease in humans and pigs: an ancient parasitosis disease rooted in developing countries and emerging as a major health problem of global dimensions.

This article reviews current knowledge on human and porcine cysticercosis caused by Taenia solium. It highlights the conditions favorable for its prevalence and transmission, as well as current trends in research on its natural history, epidemiology, immunopathology, diagnosis, treatment and prevention. Our opinions on the most urgent needs for further research are also presented.

Animals↗
PubMed2001

Relationship of third molar development and root angulation.

Angled roots are seen in mandibular third molars, which have a high frequency of incomplete impaction. We examined the relationship between incomplete impaction and angled roots. We enrolled orthopantomographs to determine the prevalence of angled roots in 239 men and 222 women aged 21--35 years with bilateral mandibular third molars. Angled roots were more frequent in subjects in whom the third molars had a different status on each side than in those with the same status on both sides (men: P<0.05; women: P<0.01). The incidence of women with angled roots in those with bilateral incomplete impactions was higher than that in those with bilateral eruption (P<0.01). Angled roots among mandibular third molars are related to environmental factors. Angled roots occur more frequently in women with incomplete impaction than in those with full eruption.

Adult↗
PubMed1995

Morphological characteristics of dentitions developing excessive root resorption during orthodontic treatment.

The present study focuses on orthodontically provoked, excessive root resorption. The purpose was to identify in these cases common morphological features in radiographic diagnostic material taken before treatment. The material was submitted by 35 Danish orthodontists. The goal was to improve the future orthodontic diagnostics of the dentition in order to prevent severe root resorption during treatment. The study indicates that: (1) there is a strong connection between various dental morphological characteristics, such as invagination, length of root, and root shapes, especially taurodontism, and the tendency to root resorption during orthodontic treatment; (2) there is a connection between anomalies in the dentition, particularly ectopia and agenesis, and the tendency to root resorption during orthodontic treatment; (3) there seems to be a connection between the pattern of resorption in the primary dentition and the tendency to root resorption in the permanent dentition following orthodontic treatment; (4) girls are more susceptible to root resorption during orthodontic treatment than boys; (5) one ought to be on the lookout for connections between condylar changes, root resorptions, and anterior open bites in connection with orthodontic treatment. The observation regarding root resorption in dentitions in which invaginations and taurodontic root shapes occur has not previously been reported. Also, the findings of deviant resorption patterns in both the primary and permanent dentitions in a considerable number of patients are new observations, which ought to be incorporated into orthodontic treatment planning.

Adolescent↗
PubMed2001

Gene expression profiling of two related maize inbred lines with contrasting root-lodging traits.

To assist breeding for increased resistance to root lodging in maize, an attempt was made to identify genes that are associated with root lodging by profiling mRNA expression from two inbreds with contrasting root-related traits. These two inbreds were derived from a common F(2) pool, selfed for several generations and showed 75% relatedness based on 106 genetic markers. Under field conditions, the two inbreds exhibited significant differences in root morphology and resistance to root lodging. Whole root tissue was collected at two developmental stages from inbred 100 and 101 grown in 2 years. RNA was isolated from both the V8 and V12 stages, a few weeks prior to flowering. The RNA samples from the 1997 growing season were analysed by GeneCalling analysis, an open-ended mRNA profiling method. From over 13 500 cDNA fragments detected from each of the V8- and V12-stage samples, 229 and 325 cDNA fragments, respectively, showed greater than 2-fold differences between the two inbred lines. A total of 69 cDNA fragments that showed 2-fold or greater differences for both inbred lines were observed at both developmental stages. The gene identity and expression differences of several cDNA fragments were determined and confirmed by RNA gel blot analysis. Two genes out of five identified were homologous to a cytochrome P450 and the impedance-induced protein, both showing high levels of expression in the roots of lodging resistant lines and low levels in the sensitive lines. These data provide the first clues of genes expressed in the roots during the formative stages of root development associated with root-lodging resistance.

Amino Acid Sequence↗
PubMed2003

Altered life cycle in Arabidopsis plants expressing PsUGT1, a UDP-glucuronosyltransferase-encoding gene from pea.

Alfalfa (Medicago sativa) and Arabidopsis were used as model systems to examine molecular mechanisms underlying developmental effects of a microsomal UDP-glucuronosyltransferase-encoding gene from pea (Pisum sativum; PsUGT1). Alfalfa expressing PsUGT1 antisense mRNA under the control of the cauliflower mosaic virus (CaMV) 35S promoter exhibited delayed root emergence, reduced root growth, and increased lateral root development. The timing of root emergence in wild-type and antisense plants was correlated with the transient accumulation of auxin at the site of root emergence. Cell suspension cultures derived from the antisense alfalfa plants exhibited a delay in cell cycle from 24-h in the wild-type plants to 48-h in the antisense plants. PsUGT1::uidA was introduced into Arabidopsis to demonstrate that, as in alfalfa and pea, PsUGT1 expression occurs in regions of active cell division. This includes the root cap and root apical meristems, leaf primordia, tips of older leaves, and the transition zone between the hypocotyl and the root. Expression of PsUGT1::uidA colocalized with the expression of the auxin-responding reporter DR5::uidA. Co-expression of DR5::uidA in transgenic Arabidopsis lines expressing CaMV35S::PsUGT1 revealed that ectopic expression of CaMV35S::PsUGT1 is correlated with a change in endogenous auxin gradients in roots. Roots of ecotype Columbia expressing CaMV35S::PsUGT1 exhibited distinctive responses to exogenous naphthalene acetic acid. Completion of the life cycle occurred in 4 to 6 weeks compared with 6 to 7 weeks for wild-type Columbia. Inhibition of endogenous ethylene did not correct this early senescence phenotype.

Arabidopsis↗