Academic literature on the topic 'Centre germinatif – Physiologie'

The National Tree Seed Centre has been providing seed of known origin and quality for research for 40 years. Seed is also stored for long-term gene conservation purposes to provide a source of germplasm for future research and restoration. This is particularly important for species facing such threats as insect attack, disease, climate change, or conversion of forest land to non-forest uses. The Centre's inventory focuses on native tree and shrub species, striving to store samples from throughout their ranges. Over 26 000 seed samples have been sent to researchers in 65 countries, 70% of these samples being distributed within Canada. Seed research has always been a component of the Seed Centre's program. One notable accomplishment is the development of the Petawawa Germination Box. The Seed Centre participates in and contributes to activities of the Association of Official Seed Analysts, the International Seed Testing Association, and the IUFRO Seed Physiology and Technology Research Group. Key words: collection, dormancy, ex situ gene conservation, germination, research, seed, storage

Aim. Study of polymorphism of alpha amylase in winter wheat varieties. Methods. Isoenzymes of alpha-amylase were detected by electrophoretic protein separation in a polyacrylamide gel. The germination index (GI) was calculated by Walker-Simmons: GI = (7xn1 + 6xn2 + ... + 1xn7) / 7 x N, where n1, n2, ..., n7 is the number of seeds sprouted on the first, second, and further days to the seventh day, respectively, N – the total number of grains. Results. Varieties were explored: Institute of Plant Physiology and Genetics of the National Academy of Sciences of Ukraine, Kiev, The Plant Breeding and Genetics Institute – National Center of Seed and Cultivar Investigation of the National Academy of Agricultural Sciences of Ukraine, Odesa and german varieties.The polymorphism of wheat grain alpha-amylase was detected by the method of electrophoretic protein separation. We searched associations between variants of alpha-amylase and resistance to pre-harvest germination, the germination index in the studied samples was determined. Conclusions. The frequency of the prevalence of variants for isoenzymes of alpha-amylase in soft wheat varieties was estimated. It was shown that genotypes containing the variant of the isoenzymes АbC are more resistant to pre-harvest germination. Among the studied varieties of PBGI NAAS and IPPG NAS of Ukraine, the variant of alpha-amylase AbC.
 Keywords: α-amylase, soft wheat, electrophoresis, varieties.

Caesalpinia pulcherrima is an exotic shrub species, belonging to the Fabaceae family, that has medicinal properties, and is widely used for urban afforestation. The objective of this research was to evaluate the overcoming of the C. pulcherrima seed dormancy, the influence of temperature, storage, and water quantity on the substrate in the germination of the species, as well as the use of the tetrazolium test for viability analysis. The analyzes were carried out at the Plant Propagation Laboratory at the Agricultural Sciences Center of the Federal University of Alagoas, in the municipality of Rio Largo, Brazil, and at the Laboratory of Plant Physiology, Arapiraca Campus, at the same University. The experiments were performed under a completely randomized design, with four replicates of 25 seeds. The results demonstrated that during storage the seeds developed a possible secondary dormancy, which was overcome with a time of twelve months of storage. The C. pulcherrima seeds subjected to the test of light qualities presented a significant difference in their germination percentage when verified with the time of storage. In the far-red quality, the newly harvested seeds had a germination percentage of (98%), higher than seeds with 12 months of storage (80.5%). The water volume 3.5-fold the weight of the dry paper provides (90%) germination when compared to other volumes. The tetrazolium salt concentrations of 0.075% and 0.1%, under the temperature of 30°C within 2 hours, are indicated for the viability analysis of Caesalpinia pulcherrima seeds.

Aim. Study of alpha amylase polymorphism in winter wheat varieties. Methods. Isoenzymes of alpha-amylase were detected by electrophoretic protein separation in a polyacrylamide gel. The fall number on the Falling Number 1700 was determined. Results. Strains from various collections were explored: Institute of Plant Physiology and Genetics of the National Academy of Sciences of Ukraine, Kiev, The Plant Breeding and Genetics Institute – National Center of Seed and Cultivar Investigation of the National Academy of Agricultural Sciences of Ukraine, Odesa and german strains. The polymorphism of wheat grain alpha-amylase was detected by the method of electrophoretic protein separation. We searched associations between variants of alpha-amylase and resistance to pre-harvest germination, the falling number in the examined samples was determined. Conclusions. The frequency of the prevalence of variants for isoenzymes of alpha-amylase in soft wheat varieties was estimated. It was shown that genotypes containing the variant of the isoenzymes АbC are more resistant to pre-harvest germination. Among the studied varieties of PBGI NAAS and IPPG NAS of Ukraine, the variant of alpha-amylase AbC.
 Keywords: α-amylase, isoenzymes, soft wheat, electrophoresis, falling number.

We made plant physiology examinations in Arkaso winter oilseed rape hybrid substance: relative chlorophyll content (SPAD) and leaf area index (LAI) measurements. The experiment was set in University of Debrecen Agricultural Sciences Center at Látóképi Experimental Station in four replications, in two different sowing times (I. sowing date on 08/22/2014 and II. sowing date on 09/09/2014 sowing againhappened because of the incomplete germination in the second subtance 01/10/2014) Three different plant density 200, 350 and 500 thousand ha-1, under the same nutrient supply, 45 cm row spacing. The experiment was green crop of winter wheat. The relative chlorophyll content (SPAD) and leaf area index (LAI) measurements were made in seven different times. We measured the maximum value of chlorophyll content in the first sowing time at 500, and the second sowing time at 350 thousand ha-1 plant density. The measurement results proved that there was a linear relationship between the number of plants and the LAI. The maximum leaf area index values we measured in both the sowing time at 500 thousand ha-1 reached.

A Petri dish assay was carried out for screening different concentrations of aqueous extracts of fresh and dry leaves of Eucalyptus citriodora on germination and seedling growth of wild oat weed (Avena fatua). Seed germination, root and shoot length of wild oat exhibited different degrees of inhibition according to the concentration of the aqueous extract. Maximum inhibitions of germination percentage, root and shoot length were recorded when using 25% fresh leaf extract. Based on this preliminary work (Petri dish assay), studies were conducted under greenhouse conditions at the National Research Center, Egypt, in the two winter seasons of 2006/2007 and 2007/2008 to evaluate the effects of foliar and soil treatments of aqueous extracts of Eucalyptus citriodora fresh and dry leaves on wild oat weed as well as on the growth and flowering of amaryllis (Hippeastrum hybridum), compared with the recommended dose of the herbicide tralkoxydim. Amaryllis fresh and dry weights as well as flowering increased significantly when treated with the previous extracts, especially the fresh leaf extract. However, the fresh and dry weights of wild oat were significantly reduced by the aqueous extracts, either fresh or dry, indicating phytotoxic effects. Tralkoxydim caused complete inhibition of wild oat as compared with the control. The studies involved estimation of the endogenous contents of total phenols in weed. With all the treatments, the inhibitory effects on weeds were correlated with accumulation of the internal contents of total phenols, compared to their respective controls. The amount of phenols correlated well with the weed's growth performance. This study establishes the effect of the aqueous extracts on the weed wild oat, associated with amaryllis, which may serve as a tool in establishing their herbicidal potential.

L'empreinte génomique, une régulation épigénétique unique entraînant une expression génique spécifique aux parents d'origine, est essentielle au développement et à la croissance des mammifères. H19 est un ARN long non codant exprimé en milieu maternel qui est un régulateur central du réseau de gènes à empreinte contrôlant le développement. H19 est exprimé pendant le développement embryonnaire dans de nombreux tissus, y compris toutes les cellules hématopoïétiques. Le rôle de H19 au cours du développement embryonnaire n'a été documenté que pour le placenta où il contrôle la croissance. Le rôle de H19 dans la lymphopoïèse n'a pas été étudié. Notre laboratoire a précédemment trouvé H19 comme principal transcrit exprimé sélectivement par les proB du foie foetal (FF), et exprimé de façon différentielle par des immigrants thymiques précoces et tardives. Cependant, le rôle du gèneH19 dans celui du développement des cellules B, ou même dans le système immunitaire, reste méconnu. Ici, nous avons réalisé une caractérisation complète des perturbations du développement et de la fonction du système immunitaire des souris pour lesquelles un grand segment du locus H19 a été supprimé. Dans cette étude, nous avons constaté que le mutant H19 avait un impact spécifique sur le développement des cellules du FF induisant une augmentation sélective du nombre des cellules proB BP1+ présentant des perturbations importantes du réarrangement du locus IgH.On observe également chez les animaux H19-/- adultes une expansion anormale du compartiment B mature. Bien que H19 ne soit plus exprimé après la naissance, les lymphocytes B des souris adultes mutantes présentent un phénotype altéré. On observe en effet des perturbations importantes du profil d'expression du marqueur B220. Les souris H19-/-présentent un défaut d'expansion des lymphocytes B du centre germinatif, ainsi qu'une chute de la production des IgM spécifiques dans le sérum après immunisation. Indiquant une réponse défectueuse des cellules B. De manière cohérente, nous avons trouvé une réactivité réduite au BCR des cellules B naïves H19-/-, associée les expériences de reconstitution compétitive ont mis en évidence un altération cellule-intrinsèque de la réponse humorale chez les animaux mutants. Un défaut d'induction de l'expression des molécules du CMHII, CD40,et CD86, qui pourrait être à l'origine des perturbations de la réponse humorale observée chez les souris H19-/-. Les analyse de transcriptome réalisées sur les lymphocytes B du centre germinal des animaux mutants ont mis en évidence une expression différentielle des gènes impliqués dans la régulation de l'intensité du signal émanant du récepteur B à l'antigène. Au total ce travail nous a permis de démontrer l'activité régulatrice exercée par l'ARN non codant H19 sur le développement et la fonction du système immunitaire<br>Genomic imprinting, a unique epigenetic regulation resulting in a parent-of-origin specificgene expression, is essential for normal mammalian development and growth. H19 is amaternally expressed long non-coding RNA that is a central regulator of the imprinting gene network controlling development and growth. H19 is expressed throughout embryonic development in multiple tissues including all hematopoietic cells. The role of H19 during embryonic development has only been documented for the placenta where it controls growthand the role of H19 in lymphopoiesis has not been investigated. The laboratory has previouslyfound H19 as the major differentially expressed transcript in two microarrays comparing fetalliver (FL) and bone marrow (BM) derived pro-B cells, as well as between early and latethymic settling progenitors. However, a role for imprinting gene H19 in B cell development,or even in immune system remains elusive. Here we sought to analyze mice where a large segment of the H19 locus has been deleted. In our work, we found that loss of H19 have specific impact on the FL B cell development byproducing increased numbers of BP1+ proB cell. Although BP1+ proB cells from H19-/- FLshowed impaired Ig heavy chain V-D-J rearrangement, that increase resulted in a net enlarged B cell compartment in the adult periphery of H19 mutant. In adult mice, although H19 is notexpressed in B lymphocytes after birth, B cells from H19-/- mice exhibited altered B cellsurface phenotype, represented by an upregulated B220 expression on all B cell subsets. After immunization with different T cell dependent antigens, H19-/- exhibits reduced GC B cells, and impaired specific IgM titer in the serum, indicating a defected B cell response in H19-/-mice. Competitive reconstitution analysis showed a B cell autonomous impairment in the Bcell response. Consistently we found a reduced BCR responsiveness of H19-/- naïve B cells that together with less efficient upregulation of MHCII and CD40 expression after immunization might be responsible for the impaired immune response in H19-/- mice. Genome-wide transcription analysis revealed differential expression of genes involved inregulating the intensity of B cell receptor signaling. This work brings new insights on the regulation role of long non-coding RNA H19 in the early B cell development and immune system