Search results for "Embryogenesi"
showing 10 items of 190 documents
Control of in vitro somatic embryogenesis of the spindle tree ( Euonymus europaeus L.) by the sugar type and the osmotic potential of the culture med…
1999
In vitro somatic embryogenesis was achieved from zygotic embryo explants of a woody angiosperm species, the spindle tree, cultivated on various culture media differing in their sugar type and concentration, or in the applied osmotic potential. The highest frequency of somatic embryogenesis was obtained with a 350 mM sucrose, or a 89 mM glucose concentration in the culture medium. Experiments with culture media differing only in osmotic potential indicated that a minimal threshold osmotic potential is required to stimulate the emergence of somatic embryos. Elevated concentrations of glucose have an inhibitory effect, independent of their osmotic effect, while elevated concentrations of sucr…
Studies on sea urchin oocytes. II. Synthesis of RNA during oogenesis.
1972
Abstract Isolated oocytes of the sea urchin Paracentrotus lividus actively incorporate 3H-uridine into RNA. Labeled RNA was analysed by sucrose gradient and acrylamide gel electrophoresis following cell fractionation. Much of the radioactivity is incorporated at the nucleolar level in the form of rRNA precursors. The kinetics of maturation of these latter suggests that this occurs at a slower rate than during embryogenesis. Other non-nucleolar RNA classes are also actively labelled and retained in the nucleus for many hours. These results are confirmed by an autoradiographic investigation.
Genome-wide analysis of the repertoire of TRIM genes in sea urchins
2012
The eukaryotic TRIM (TRIpartite Motif) super-family represents one of the largest classes of putative E3 ubiquitin ligases involved in several processes, including epigenetic control of development and disease. In the post-genomic era, new approaches allow genome-wide studies of gene family. In particular, we performed a comprehensive analysis of the TRIM repertoire in selected sea urchin species. By combining iterations of ab initio predictions and pairwise comparative methods, we first retrieved the full complement of TRIM genes in Strongylocentrotus purpuratus, whose full genome sequence was available. Interestingly, such a DNA sequence set includes not previously classified, echinoderm-…
Characterization of Leaf Essential Oil Composition of Homozygous and HeterozygousCitrus clementinaHort. Extan. and its Ancestors
2013
Clementine is a natural tangor, resulting from an interspecific cross between mandarin and sweet orange. Gametic embryogenesis, allowing the single-step development of complete homozygous line from the heterozygous parents, increases the efficiency of perennial crop breeding programs. Tri-haploids have been regenerated through pollen embryogenesis (specifically, by anther culture) of Citrus clementina Hort. ex Tan., cv. Nules. Two of them (HOMO1 and HOMO2) have been acclimatized and grafted in vivo in 2000. Research regarding the chemical characteristics of plant regenerated by pollen embryogenesis or gynogenesis are useful to study the “gametoclonal variation”, as well as for further appli…
Morphological and anatomical observations of abnormal somatic embryos from anther cultures of Citrus reticulata
2010
A morphological and anatomical study of regenerants obtained from mandarin anther culture was carried out. Beside morphologically normal somatic embryos, abnormal structures were originated in the course of somatic embryogenesis. Anatomical anomalies can be found at several growth stages, causing the formation of slender stems, stubby structures, non-functional leaves. When too long, some structures are subject to shedding, with the formation of various abscission zones. Most of them are subject to degeneration, although many are capable of further, localized, morphogenesis. A thorough knowledge of morphology and anatomy of normal and abnormal regenerants could make possible to select and s…
Experimental change of cytoplasmic composition can convert determination of blastomeres inPlatynereis dumerilii (Annelida, Polychaeta)
1991
Early development ofPlatynereis dumerilii is characterized by an extremely constant cleavage pattern in which the volumes and cytoplasmic contents of the blastomeres show remarkably little variability (Dorresteijn 1990). In order to test the necessity of a precise partitioning of the cytoplasm, we have stratified the ooplasm by mild centrifugation (10 min at 300 g) after completion of meiosis but before first cleavage. The cytoplasm of the zygote stratifies randomly with respect to the pre-existing animal-vegetal axis, but first cleavage follows the animal-vegetal axis dividing the plasm before it has rearranged to its normal distribution. As usual, first cleavage is unequal in the majority…
Stimulation of root and somatic embryo production in Euconymus europaeus L. by an inhibitor of polyamine biosynthesis
1995
In vitro formation of roots and somatic embryos is obtained from cotyledon explants of a Spindle tree (Euonymus europaeus L.) cultured on two different media: a medium inducing callus formation and the production of roots, and a medium inducing callus formation, root and somatic embryo production. We studied the effects of α-difluoromethylornithine (DFMO), a specific, irreversible inhibitor of ornithine decarboxylase (ODC) on root and somatic embryo production, growth and titers of putrescine in Euonymus explants and explant-derived calli. Early changes in putrescine levels were detected in both cultures before the visible emergence of roots or somatic embryos. DFMO rapidly inhibited putres…
How does sulfur deficiency modulate pea response to water stress? Impact on early developing and mature seeds
2018
National audience; Pea (Pisum sativum L.) produces seeds rich in proteins but yield and quality remain unstable across years due to various stresses. Sulfur (S) deficiency and water stress are two abiotic stresses that interact in the current context of climate change and low-input practices, and recent studies suggest an important role for sulfate transport and metabolism in the plant response to water stress. To investigate the interplay between sulfur nutrition and the water stress response, sulfate-deprived pea plants were subjected to a 9-days period of water stress during the early reproductive phase. While water stress did not impact seed yield, sulfur deficiency alone or combined wi…
Correlating stress and somatic embryogenesis for NBT: myth or reality?
2018
Global warming and growing demography have increased demand for agronomic resources, leading to increasing lack of land suitable for agriculture and provoking several abiotic stresses which, added to biotic ones, result in physiological and metabolic disorders that impact on crop yield when most needed. Reducing this impact is a major scientific and agronomic challenge and biotechnology would be an efficient alternative. However, to reduce risks of somaclonal variation among regenerants it is better to produce them by somatic embryogenesis directly from explants or gametes, or indirectly from callus or cell suspensions. Thus, globular embryos regenerate and develop through to the heart, tor…
Changes in the pea seed proteome in response to drought combined with sulfur deficiency
2017
EABAPGEAPSI DOCT INRA; Pea (Pisum sativum L.) produces seeds rich in proteins, but seed yield and quality remain unstable across years due to abiotic stresses occurring during the reproductive period. Drought and sulfur deficiency are two abiotic stresses that interact in the current context of climate change and lowinput practices, and recent studies suggest a role of sulfate transport and metabolism in the plant response to drought (Ernst et al., 2010; Chan et al., 2013; Gallardo et al., 2014; Ahmad et al., 2016). In this study, we investigated the impact of sulfur deficiency combined with drought on the pea seed proteome. Pea plants were subjected to sulfur-deficiency two weeks after sow…