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Nicotiana ovule extracts induce nuclear reconstitution of demembranated Xenopus sperm in cell-free system
Ping Lu,Min Ren,Zhonghe Zhai
Chinese Science Bulletin , 2002, DOI: 10.1360/02tb9072
Abstract: Nicotiana tabaccum ovule extracts induced nuclear reconstitution of demembranated Xenopus leavis sperm in a cell-free system. Demembranated Xenopus sperm began to swell after 15 min of incubation with Nicotiana ovule extracts. Accompanying the process of incubation, Xenopus sperm decondensed and their shapes changed gradually from long and ellipse to round. The completely decondensed chromatin was surrounded with membrane structure, which was a mixture envelope of a double membrane and a single membrane. Nucleosome assembly was verified by means of micrococcal nuclease digestion to reconstituted nuclei and DNA electrophoresis. Nicotiana ovule extracts supplied one more experimental model and system. The new system could promote powerfully the research on mechanisms of cell division and cell cycle regulation.
Reconstitution of the Costunolide Biosynthetic Pathway in Yeast and Nicotiana benthamiana  [PDF]
Qing Liu, Mohammad Majdi, Katarina Cankar, Miriam Goedbloed, Tatsiana Charnikhova, Francel W. A. Verstappen, Ric C. H. de Vos, Jules Beekwilder, Sander van der Krol, Harro J. Bouwmeester
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023255
Abstract: The sesquiterpene costunolide has a broad range of biological activities and is the parent compound for many other biologically active sesquiterpenes such as parthenolide. Two enzymes of the pathway leading to costunolide have been previously characterized: germacrene A synthase (GAS) and germacrene A oxidase (GAO), which together catalyse the biosynthesis of germacra-1(10),4,11(13)-trien-12-oic acid. However, the gene responsible for the last step toward costunolide has not been characterized until now. Here we show that chicory costunolide synthase (CiCOS), CYP71BL3, can catalyse the oxidation of germacra-1(10),4,11(13)-trien-12-oic acid to yield costunolide. Co-expression of feverfew GAS (TpGAS), chicory GAO (CiGAO), and chicory COS (CiCOS) in yeast resulted in the biosynthesis of costunolide. The catalytic activity of TpGAS, CiGAO and CiCOS was also verified in planta by transient expression in Nicotiana benthamiana. Mitochondrial targeting of TpGAS resulted in a significant increase in the production of germacrene A compared with the native cytosolic targeting. When the N. benthamiana leaves were co-infiltrated with TpGAS and CiGAO, germacrene A almost completely disappeared as a result of the presence of CiGAO. Transient expression of TpGAS, CiGAO and CiCOS in N. benthamiana leaves resulted in costunolide production of up to 60 ng.g?1 FW. In addition, two new compounds were formed that were identified as costunolide-glutathione and costunolide-cysteine conjugates.
Reconstitution of licensed replication origins on Xenopus sperm nuclei using purified proteins
Peter J Gillespie, Anatoliy Li, J Julian Blow
BMC Biochemistry , 2001, DOI: 10.1186/1471-2091-2-15
Abstract: Here we show that a combination of purified nucleoplasmin, the origin recognition complex (ORC), Cdc6, RLF-B/Cdt1 and Mcm2-7 can promote functional origin licensing and the assembly of Mcm2-7 onto Xenopus sperm nuclei. The reconstituted reaction is inhibited by geminin, a specific RLF-B/Cdt1 inhibitor. Interestingly, the purified ORC used in the reconstitution had apparently lost the Orc6 subunit, suggesting that Orc6 is not essential for replication licensing. We use the reconstituted system to make a preliminary analysis of the different events occuring during origin assembly, and examine their nucleotide requirements. We show that the loading of Xenopus ORC onto chromatin is strongly stimulated by both ADP, ATP and ATP-γ-S whilst the loading of Cdc6 and Cdt1 is stimulated only by ATP or ATP-γ-S.Nucleoplasmin, ORC, Cdc6, RLF-B/Cdt1 and Mcm2-7 are the only proteins required for functional licensing and the loading of Mcm2-7 onto chromatin. The requirement for nucleoplasmin probably only reflects a requirement to decondense sperm chromatin before ORC can bind to it. Use of this reconstituted system should allow a full biochemical analysis of origin licensing and Mcm2-7 loading.During S phase of the eukaryotic cell division cycle the entire genome must be faithfully duplicated. The many thousands of replication forks involved in this process must be co-ordinated to ensure that, despite the very large quantities of DNA involved, no section of DNA is left unreplicated and no section of DNA is replicated more than once. Cells achieve this by dividing the process of replication origin activation into two distinct phases [1-3]. During late mitosis and early G1, proteins are assembled onto replication origins which culminates in the origin becoming 'licensed' for a single round of DNA replication by loading complexes of Mcm2-7 proteins [4-8]. In yeast, a 'pre-replicative complex' (pre-RC) forms a footprint over replication origins during G1 [9] which may well correspond to
An ontology for Xenopus anatomy and development
Erik Segerdell, Jeff B Bowes, Nicolas Pollet, Peter D Vize
BMC Developmental Biology , 2008, DOI: 10.1186/1471-213x-8-92
Abstract: We have constructed a Xenopus anatomical ontology that represents the lineage of tissues and the timing of their development. We have classified many anatomical features in a common framework that has been adopted by several model organism database communities. The ontology is available for download at the Open Biomedical Ontologies Foundry http://obofoundry.org webcite.The Xenopus Anatomical Ontology will be used to annotate Xenopus gene expression patterns and mutant and morphant phenotypes. Its robust developmental map will enable powerful database searches and data analyses. We encourage community recommendations for updates and improvements to the ontology.The African clawed frog, Xenopus laevis, is a widely used model organism in developmental biology and the related species Xenopus (Silurana) tropicalis has emerged as an important model for genetics. The quickly developing embryos of Xenopus, which form a full set of differentiated tissues within days of fertilization, have been described in fine detail [1] and are highly amenable to analysis of embryonic gene function. High throughput screens of gene expression patterns by whole mount in situ hybridization in X. laevis [2,3] and morpholino-based gene-knockdown experiments [4,5] have generated a vast set of gene function data. These data are crucial to ongoing Xenopus research efforts and they complement the gene expression and gene function information that is available for other model systems. Consequentially a need has emerged for a centralized database of Xenopus information, and with it, in order to organize tissue-specific data, a formalized specification of knowledge about Xenopus anatomy throughout the organism's development. Biomedical ontologies offer distinct advantages for annotating and disseminating biological data, representing areas of knowledge such as gene function, genetic sequence features and anatomy as structured, controlled vocabularies [6] and giving researchers and informaticians the
Ovule development, a new model for lateral organ formation  [PDF]
Mara Cucinotta,Lucia Colombo,Irma Roig-Villanova
Frontiers in Plant Science , 2014, DOI: 10.3389/fpls.2014.00117
Abstract: In spermatophytes the ovules upon fertilization give rise to the seeds. It is essential to understand the mechanisms that control ovule number and development as they ultimately determine the final number of seeds and, thereby, the yield in crop plants. In Arabidopsis thaliana, ovules arise laterally from a meristematic tissue within the carpel referred to as placenta. For a correct determination of the number of ovules, a precise establishment of the positions where ovule primordia emerge is needed, and a tight definition of the boundaries between ovules is therefore also required. In the last decades, few factors have been identified to be involved in the determination of ovule number. Recently, plant hormones have also been revealed as fundamental players in the control of the initiation of ovule formation. In this review we summarize the current knowledge about both the molecular and hormonal mechanisms that control ovule formation in Arabidopsis thaliana.
The Molecular and Genetic Control of Ovule Morphogenesis

植物学报 , 2005,
Abstract: The ovule has been used as an excellent model system to study morphogenesis and organogenesis. Progress has been made in investigating the molecular mechanisms of several aspects of ovule development, such as identity control, early pattern formation, integument morphogenesis, and embryo sac development. A genetic network that controls the ovule development process is presented. In addition, the in vitro floral regeneration system is useful for studying the regulation of ovule development by plant hormones. This paper reviews the progress made in the investigation of ovule development.
Expression-based discovery of candidate ovule development regulators through transcriptional profiling of ovule mutants
Debra J Skinner, Charles S Gasser
BMC Plant Biology , 2009, DOI: 10.1186/1471-2229-9-29
Abstract: Affymetrix microarrays were used for expression-based gene discovery to identify sets of genes expressed in either or both integuments. The genes were identified by comparison of pistil mRNA from wild type with mRNA from two mutants; inner no outer (ino, which lacks the outer integument), and aintegumenta (ant, which lacks both integuments). Pools of pistils representing early and late stages of ovule development were evaluated and data from the three genotypes were used to designate genes that were predominantly expressed in the integuments using pair-wise and cluster analyses. Approximately two hundred genes were found to have a high probability of preferential expression in these structures, and the predictive nature of the expression classes was confirmed with reverse transcriptase polymerase chain reaction and in situ hybridization.The results showed that it was possible to use a mutant, ant, with broad effects on plant phenotype to identify genes expressed specifically in ovules, when coupled with predictions from known gene expression patterns, or in combination with a more specific mutant, ino. Robust microarray averaging (RMA) analysis of array data provided the most reliable comparisons, especially for weakly expressed genes. The studies yielded an over-abundance of transcriptional regulators in the identified genes, and these form a set of candidate genes for evaluation of roles in ovule development using reverse genetics.Ovules, the precursors to seeds, are an important focus of study to better understand plant development within a unique reproductive context. Ovules are highly specialized for reproductive function, but the typical angiosperm ovule, as found in Arabidopsis, is relatively simple morphologically. Development of the ovule within the carpel is well described, [1-5], beginning with primordia emergence from the marginal placentas of the carpels (floral stage 9, ovule stage 1). The primordia have three regions, the distal region or nucellus, ma
Molecular Bases of Ovule Development

ZHANG Xian-Sheng,MA Xiao-Jie,GUO Hai-Xin,

植物学报 , 1998,
Abstract: The ovule is the source of the embryo sac and the progenitor of the seed, which plays an important role on plant reproduction. A few mutants had been identified in recent years, such as sin l, bell, ovm2, ovm3,whose phenotypes show that both integuments and embryo sac develop abnormally,and these mutants are female-sterile. At the same time, some ovule-specific cDNA clones in Orchid and Petunia flowers had been isolated and among them MADS Box genes may be responsible for the ovule differentiation and formation.
Immune reconstitution inflammatory syndrome  [cached]
Sharma Ajay,Makrandi Smita,Modi Megha,Sharma Archana
Indian Journal of Dermatology, Venereology and Leprology , 2008,
Abstract: Background: Immune reconstitution inflammatory syndrome (IRIS) is a paradoxical deterioration in clinical status in a patient on antiretroviral treatment (ART) despite satisfactory control of viral replication and improvement of CD4 count. Aim: To study development of IRIS as a part of ART. Methods: Hundred patients on antiretroviral treatment were studied prospectively in the Department of Skin and VD over a period of 2 years. Patients were asked to come if they developed any symptoms or on a monthly basis. They were screened clinically and investigated suitably for evidence of opportunistic infections. Results: Out of 100 patients, 10 patients did not come for follow-up. Twenty (22.2%) out of the 90 patients developed IRIS. Herpes zoster (HZ), herpes simplex virus (HSV), and tuberculosis (TB) were the cases of IRIS seen in the present study. Conclusions: IRIS in terms of HSV/TB is known to accelerate HIV disease progression. Hence early detection and prompt treatment, along with continuation of highly active ART, are of utmost importance.
Ovule ontogenesis and megasporogenesis in Adesmia latifolia (Spreng.) Vog. (Leguminosae-Papilionoideae)
Mo?o, Maria C.C.;Mariath, Jorge E.A.;
Brazilian Journal of Botany , 2003, DOI: 10.1590/S0100-84042003000400008
Abstract: the ovule ontogenesis and the megasporogenesis events were studied under bright field, fluorescence and scanning electron microscopy. the primordium is 3-zonate and gives rise to a hemianatropous, bitegmic and crassinucellate ovule. the archesporium may consist of one or more archesporial cells, but only one undergoes meiosis, forming a linear tetrad. normally, only a single megaspore is functional in the chalazal position, but occasionally two functional chalazal megaspores arise. the present study provides additional information on embryological characters in the adesmieae tribe and discusses their taxonomic significance to the leguminosae family.
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