103,022 research outputs found
ANNOTATION AND EXPRESSION OF FDM-LIKE GENES IN SEXUAL AND APOMICTIC H. PERFORATUM ACCESSIONS
No full textApomixis is an asexual reproductive strategy that permits to the inheritance of the maternal
genome over generations without genetic recombination events. From a biological point of view,
this modality of asexual reproduction by seed could be the consequence of heterocronic expression
of genes involved in fundamental aspects of sexual reproduction, such as meiosis and spore
selection, leading to the formation of functional un-reduced gametes which retain the ability to form
an embryo eventually bypassing double fertilization. Although this process is well documented in
many flowering plants, and despite its revolutionary potentials in plant breeding strategies, the
genetic control of apomixes is still not properly understood. Recently, a number of independent
studies on sexual model species provided experimental evidences linking single components of
apomixis to the deregulation of genes involved in the RNA-directed DNA methylation pathway
(RdDM). RNA-directed DNA methylation refers to a specific process in which small interfering
RNAs produced by the RNA interference pathway guide de novo methylation of cytosines at the
homologous DNA region, thereby regulating the expression of specific genes. Remarkably, gene
expression studies in the apomictic model species Hypericum perforatum corroborate the
hypothesis that miss expression of genes involved in this pathway is functionally associated with
early events of apomixes in this species. The aim of the present research is a better understanding of
the role of a class of genes involved in the RdDM known as Factor of DNA Methylation (FDM), in
the frame of ovule cell fate change, megagametogenesis and, ultimately, aposporous apomixis. To
this end, computational investigations were performed in order to annotate the H. perforatum FDM
genes. The expression of these genes in H. perforatum pistils and ovules was studied by qPCR and
ISH assays on sexual and apomictic accessions. Furthermore, Arabidopsis thaliana knock out lines
were characterized in order to elucidate the role of specific genes in relation to gametophyte and/or
seed formation. All data will be presented and critically discussed as they prove a better
understanding of molecular bases of apomixes in H. perforatum
Author Correction: Uncovering the sources of DNA found on the Turin Shroud
No full textAn amendment to this paper has been published and can be accessed via a link at the top of the paper
Annotation and Expression of IDN2-like and FDM-like genes in sexual and aposporous hypericum perforatum L. Accessions
No full textThe protein IDN2, together with the highly similar interactors FDM1 and FDM2, is required for RNA-directed DNA methylation (RdDM) and siRNA production. Epigenetic regulation of gene expression is required to restrict cell fate determination in A. thaliana ovules. Recently, three transcripts sharing high similarity with the A. thaliana IDN2 and FDM1-2 were found to be differentially expressed in ovules of apomictic Hypericum perforatum L. accessions. To gain further insight into the expression and regulation of these genes in the context of apomixis, we investigated genomic, transcriptional and functional aspects of the gene family in this species. The H. perforatum genome encodes for two IDN2-like and 7 FDM-like genes. Differential and heterochronic expression of FDM4-like genes was found in H. perforatum pistils. The involvement of these genes in reproduction and seed development is consistent with the observed reduction of the seed set and high variability in seed size in A. thaliana IDN2 and FDM-like knockout lines. Differential expression of IDN2-like and FDM-like genes in H. perforatum was predicted to affect the network of potential interactions between these proteins. Furthermore, pistil transcript levels are modulated by cytokinin and auxin but the effect operated by the two hormones depends on the reproductive phenotype
ANNOTATION AND EXPRESSION OF FDM-LIKE GENES IN SEXUAL AND APOMICTIC MODEL SPECIES
No full textAposporous apomixis is a reproductive strategy that leads to seed production by avoiding
female sporogenesis and, eventually, fertilization. In this peculiar reproductive strategy, embryo and
endosperm are formed from unreduced gametes developing from somatic cells belonging to the
ovule nucellus. Recently gained information on ovule gene expression in the apomictic model
species Hypericum perforatum L. demonstrated that a few genes involved in the RNA-directed
DNA methylation pathway (RdDM) are differentially expressed in ovules collected from apomictic
accessions at pre-meiotic stages. In A. thaliana, the protein Involved in De Novo 2 (IDN2), together
with members of the gene family Factors of DNA Methylation (FDM1, FDM2), acts downstream of
the RdDM. In this pathway, IDN2/FDM complex are recruited to the chromatin by the ra-siRNAPol V transcript duplex, and then bind the un-methylated DNA to promote DNA methylation of
both transposons and protein coding genes. Remarkably, the knock-out of genes involved in the
RdDM in sexually reproducing species such as A. thaliana and Z. mays results in phenotypes
mimicking early events of aposporous apomixis. Taken together, these findings let us to
hypothesize that RNA-directed DNA methylation might be involved in correct patterning of cell
fate determination in the ovule in sexual and apomictic species. This research focuses on genes
belonging to the gene family known as Factors of DNA Methylation (FDM1-5) and their closely
related IDN2 (Involved in De Novo 2). Our research aim is a better understanding of roles played
by these genes in the frame of ovule cell fate determination and gametes formation.
Bioinformatics analyses were performed in order to identify and annotate all gene family
members expressed in H. perforatum ovules. Gene expression differences between pistils collected
from sexual and apomictic accessions were confirmed by qPCR and ISH. Correlated experiments
were performed by taking advantage of mutant lines available for A. thaliana. IDN2 and FDM1-5
knockout lines were analyzed for alterations in total seed set and plant habits. Mutant lines
displayed overlapping phenotypes, including the reduction of seed set. Overall, our phenotypic data
are in line with a sporophytic effect resulting in the ovule abortion in A. thaliana. GUS reporter
lines were adopted to visualize the FDM promoter activity in ovules at different developmental time
points. Furthermore, the development of a protocol suitable for whole-mount qPCR assays allowed
rapid and reliable quantification of gene expression in micro-dissected ovules. Our results elucidate
the role of FDM and IDN2 genes in both sexual and apomicts plants and add new factors affecting
the complex events involved in ovule and gametes formation that should be further investigated
TRANSCRIPTOMIC ANALYSIS OF OVULE-SPECIFIC CELL LINEAGES TO IDENTIFY GENES RELATED TO APOSPOROUS APOMIXIS IN HYPERICUM PERFORATUM L.
No full textThe medicinal plant St. John’s wort (Hypericum perforatum L.) is an attractive model system
for the study of aposporous apomixis. The key biological features of apomixis in this species are the
by-passing of meiosis, the differentiation of aposporous initials into embryo sacs containing
unreduced egg cells, their autonomous development in functional embryos without fertilization, and
the formation of viable endosperm either via fertilization-independent means or following
fertilization with a sperm nucleus. The aim of this research is to define gene expression changes
occurring in the nucellar cell types of the ovules primarily involved in the differentiation of the
megaspore mother cells and aposporous initials. To this end, a laser-capture microdissection
approach was adopted in combination with the RNA-seq technology in order to restrict the frame of
our investigations to a specific portion of the ovule, i.e. the nucellus, at developmental stages
preceding the differentiation of aposporous initials. Overall, our gene expression analysis identified
270 and 81 unigenes that were found significantly up- and down-regulated between ovules collected
from sexual and apomictic accessions. Ontological annotation of differentially expressed genes
indicated that genes up-regulated in apomictic ovules were significantly enriched in ontological
terms related to the RNA-directed DNA polymerase activity and the RNA binding. Among these
genes, several actors of the RdDM pathway were found, suggesting that the phenotypic expression
of early events of aposporous apomixis is associated to changes in de novo DNA methylation
mediated by small RNAs. Furthermore, as deregulation of single components of the sexual
developmental pathway is believed to be a trigger of the apomictic reproductive program, genes
involved in sporogenesis, gametogenesis and response to hormonal stimuli were annotated and
investigated in great detail. The expression analysis of candidate genes was performed not only by
Real-Time qPCR but also by ISH assays in order to verify the temporal and spatial expression
patterns of selected transcripts in the ovule. Finally, the activity of specific genes in relation to
embryo sac and/or embryo formation was investigated by using A. thaliana knock-out lines.
Overall, our data suggest that phenotypic expression of aposporous apomixis is concomitant with
the modulation of key genes involved in the sexual reproductive pathway, hormones and other
actors likely playing a crucial role in the RNA-directed DNA methylation pathway
Uncovering the sources of DNA found on the Turin Shroud
No full textThe Turin Shroud is traditionally considered to be the burial cloth in which the body of Jesus Christ was wrapped after his death approximately 2000 years ago. Here, we report the main findings from the analysis of genomic DNA extracted from dust particles vacuumed from parts of the body image and the lateral edge used for radiocarbon dating. Several plant taxa native to the Mediterranean area were identified as well as species with a primary center of origin in Asia, the Middle East or the Americas but introduced in a historical interval later than the Medieval period. Regarding human mitogenome lineages, our analyses detected sequences from multiple subjects of different ethnic origins, which clustered into a number of Western Eurasian haplogroups, including some known to be typical of Western Europe, the Near East, the Arabian Peninsula and the Indian sub-continent. Such diversity does not exclude a Medieval origin in Europe but it would be also compatible with the historic path followed by the Turin Shroud during its presumed journey from the Near East. Furthermore, the results raise the possibility of an Indian manufacture of the linen cloth
Evaluation of Analgesic and Anti-Inflammatory Activities of Water Extract of<i> Galla Chinensis In Vivo</i> Models
No full textAim. Pain and inflammation are associated with many diseases in humans and animals. Galla Chinensis, a traditional Chinese medicine, has a variety of pharmacological properties. The purpose of this study was to evaluate analgesic and anti-inflammatory activities of Galla Chinensis through different animal models. Method. The analgesic activities were evaluated by hot-plate and writhing tests. The anti-inflammatory effects were assessed by ear edema, capillary permeability, and paw edema tests. The contents of cytokines (NO, iNOS, PGE2, and IL-10) in serum of rats in paw edema test were inspected by ELISA assays. Results. In the hot-plate test, Galla Chinensis could significantly extend pain threshold when compared to control group. The inhibitory rates of writhes ranged from 36.62% to 68.57% in Galla Chinensis-treated mice. Treatment with Galla Chinensis (1 and 0.5 g/kg) could significantly inhibit ear edema (47.45 and 36.91%, resp.; P < 0.01). Galla Chinensis (1 g/kg) had significant (P < 0.05) anti-inflammatory activity in capillary permeability test (29.04%). In carrageenan-induced edema test, the inhibitory rates were 43.71% and 44.07% (P < 0.01) at 1 h and 2 h after administration of Galla Chinensis (1 g/kg), respectively, and the levels of proinflammatory cytokines were significantly reduced. Conclusion. These results suggest that Galla Chinensis has analgesic and anti-inflammatory effects, which may be a candidate drug for the treatment of inflammation and pain.</jats:p
Felci raccolte da G. Cei nel territorio dei Galla e Sidama e cenni sulle loro stazioni
No full textG. Cei traccia l’itinerario seguito e descrive le caratteristiche principali del paesaggio vegetale del territorio dei Galla e Sidama.
R. Pichi Sermolli illustra le felci raccolte in tale viaggio, descrivendo una specie nuova, Asplenium Ceii, e segnalando 10 specie non ancora note dell’A.O.I.; aggiunge alcune considerazioni fitogeografiche sulla foresta del Caffa, che ascrive al tipo di foresta pluviale montana.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse
Felci raccolte da G. Cei nel territorio dei Galla e Sidama e cenni sulle loro stazioni
No full textG. Cei traccia l’itinerario seguito e descrive le caratteristiche principali del paesaggio vegetale del territorio dei Galla e Sidama.
R. Pichi Sermolli illustra le felci raccolte in tale viaggio, descrivendo una specie nuova, Asplenium Ceii, e segnalando 10 specie non ancora note dell’A.O.I.; aggiunge alcune considerazioni fitogeografiche sulla foresta del Caffa, che ascrive al tipo di foresta pluviale montana.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse
Il Mausoleo di Galla Placidia. Indagini conoscitive e trattamenti manutentivi del paramento murario esterno.
No full textNell'articolo vengono riguardanti il Mausoleo di Galla Placidia di Ravenna, vengono illustrate le indagini coscitive e il progetto di restauro che ha interessato il paramento murario esterno
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