Search results for "Genesis"
showing 10 items of 12136 documents
Linking present environment and the segregation of reproductive modes (geographical parthenogenesis) in Eucypris virens (Crustacea: Ostracoda)
2013
Aim Geographical parthenogenesis – in which parthenogenetic populations are more widely distributed than sexually reproducing populations – is observed in many plant and animal species. Many hypotheses have been proposed to account for this biogeographical pattern, and these often invoke historical processes such as the influence of glaciation. However, there are relatively few empirical studies of the contemporary factors associated with geographical parthenogenesis. The aim of this study was to understand its causes by linking contemporary environmental gradients with reproductive modes in the freshwater ostracod Eucypris virens. Location Europe and North Africa. Methods We sampled popula…
Phytotoxicity and metabolism of chlortoluron in two wheat varieties
1985
Abstract Varietal susceptibility of winter wheat to chlortoluron, 1-(3-chloro-4-methylphenyl)-3,3 dimethylurea, has been studied in two varieties, Corin (susceptible) and Clement (tolerant). After a 24-hr root absorption of the herbicide, phytotoxicity was estimated from growth measurements. When administered at 12 to 96 μM concentrations, the herbicide reduced the growth of both varieties. A significant selective effect was found at 96 μM. Measurements of chlorophyll fluorescence-induction kinetics allowed to discriminate between the two varieties treated with 12 to 48 μM chlortoluron. The metabolism of chlortoluron was studied following absorption of 24 μM solutions. Both varieties produc…
Effects of magnesium deprivation on development and biomineralization in the sea urchin Arbacia lixula
2019
Echinoderms have an extensive endoskeleton composed of magnesian calcite and occluded matrix proteins. As biomineralization in sea urchin larvae is sensitive to the Magnesium:Calcium ratio of seawater, we investigated the effects of magnesium deprivation on development and skeletogenesis in the sea urchin Arbacia lixula. We focused on the localization of the skeletogenic cells (primary mesenchyme cells) and the spatial expression of associated genes. Embryos reared in Mg-free seawater exhibited developmental delay from 6-h post-fertilization and at 24 h embryos showed complete lack of biomineral formation. Larvae (48–72 h) exhibited severe skeleton malformations. Fluorescent labelling revea…
Doubled haploid production in onion (Allium cepa L.): from gynogenesis to chromosome doubling
2020
Bulb onion (Allium cepa L.) is an allogamous diploid (2n = 16) important for its culinary uses, nutritional value, and medicinal benefits. Despite its economic importance, onion yields and bulb quality are declining, emphasizing the need for new and improved strategies for maintaining and enhancing overall crop quality. Development of inbred lines in onion through traditional breeding is often difficult due to its biennial life cycle, inbreeding depression, and comparatively high heterozygosities. Moreover, genetic research in onion has been hampered by large nuclear genome size. In this regard, gynogenic doubled haploids promise several advantages over inbred lines in support of onion bree…
Early changes in gene expression in tobacco cells elicited with cryptogein
1995
48 ref.; International audience
Life history and spatial distribution of the enchytraeid wormCognettia sphagnetorum(Oligochaeta) in metal-polluted soil: Below-ground sink-source pop…
2001
We studied the life history, metal-avoidance behavior, spatial distribution, and population growth of enchytraeid worms (Cognettia sphagnetorum [Oligochaeta]) originating from two sites: one uncontaminated, and another patchily polluted by heavy metals. Effects of patchy soil contamination on populations were studied in microcosms. In uncontaminated soil, worms from the polluted site had lower viability and reduced growth rate as juveniles but higher growth rate as adults compared to worms from the unpolluted site. They were also smaller in size at fragmentation (reproduction). Worms from the polluted site reached a larger population size than worms from the unpolluted site. Hence, worms fr…
Effects of Acifluorfen-methyl on cucumber cotyledons : porphyrin accumulation
1988
Abstract The nitrodiphenyl ether herbicide acifluorfen-methyl and the pyridine derivative LS 82-556 induce porphyrin accumulation in green cucumber cotyledons. When experiments are done with intact plants absorbing the herbicide through the roots, that accumulation is light-dependent. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) which prevents cellular damages under these conditions (M. Matringe and R. Scalla, Pestic. Biochem. Physiol. 26 , 150 (1986), also inhibits porphyrin accumulation. In contrast, when detached cotyledons are cut into pieces and floated on herbicide solutions, porphyrins accumulate in the dark. Accordingly, DCMU does not inhibit porphyrin accumulation or protect the …
Can phthalates move into the eggs of the loggerhead sea turtle Caretta caretta? The case of the nests on the Linosa Island in the Mediterranean Sea
2021
During the monitoring of Caretta caretta nests on the island of Linosa, 30 unhatched eggs from four nests were collected to study the presence of phthalates in their three components (shell, yolk, and albumen). Four phthalates, namely diethyl (DEP), dibutyl (DBP), di-(2-ethylhexyl) (DEHP), and dioctyl (DOTP) phthalic acid esters (PAE), which are widely used as additives in plastics, were detected in all egg components. The most frequently found phthalate was DBP, followed by DEHP in eggshell and yolk. Dimethyl- (DMP) and butylbenzyl-phthalate (BBP) were below the limits of detection for all samples. The high total phthalate recorded in the yolk suggests that contamination could arise by vit…
Direct exposure to solar radiation causes radial growth eccentricity at the beginning of the growing season in Robinia pseudoacacia
2020
Abstract Our study investigated the effect of stem temperature increase on xylem formation in Robinia pseudoacacia tree-trunks, caused by direct exposure to solar radiation. It is important to determine factors which may improve the concentricity of deposited wood tissue and intensify xylogenesis because a strong irregularity of wood tissue deposited in the radial direction in mature trees of R. pseudoacacia reduces the commercial value of the wood. Samples of vascular cambium along with adjacent tissues were collected from the southern (illuminated) and northern (shaded) side of tree-trunks growing in the inner and peripheral (thus exposed to direct sunlight) zones of the research plot. Sa…
The evolution, diversity and host associations of rhabdoviruses
2015
Metagenomic studies are leading to the discovery of a hidden diversity of RNA viruses, but new approaches are needed predict the host species these poorly characterised viruses pose a risk to. The rhabdoviruses are a diverse family of RNA viruses that includes important pathogens of humans, animals and plants. We have discovered the sequences of 32 new rhabdoviruses through a combination of our own RNA sequencing of insects and searching public sequence databases. Combining these with previously known sequences we reconstructed the phylogeny of 195 rhabdovirus sequences producing the most in depth analysis of the family to date. In most cases we know nothing about the biology of the viruses…