Search results for "developmental"
showing 10 items of 19870 documents
Belnapia mucosa sp. nov. and Belnapia arida sp. nov., isolated from desert biocrust
2021
Two novel Gram-staining-negative, aerobic, cocci-shaped, non-motile, non-spore forming, pink-pigmented bacteria designated strains T6T and T18T, were isolated from a biocrust (biological soil crust) sample from the vicinity of the Tabernas Desert (Spain). Both strains were catalase-positive and oxidase-negative, and grew under mesophilic, neutrophilic and non-halophilic conditions. According to the 16S rRNA gene sequences, strains T6T and T18T showed similarities with Belnapia rosea CGMCC 1.10758T and Belnapia moabensis CP2CT (98.11 and 98.55% gene sequence similarity, respectively). The DNA G+C content was 69.80 and 68.96% for strains T6T and T18T, respectively; the average nucleotide iden…
Evidence for specific, high-affinity binding sites for a proteinaceous elicitor in tobacco plasma membrane
1995
Abstract Binding of cryptogein, a proteinaceous elicitor, was studied on tobacco plasma membrane. The binding of the [125I]cryptogein was saturable, reversible and specific with an apparent Kd of 2 nM. A single class of cryptogein binding sites was found with a sharp optimum pH for binding at about pH 7.0. The high-affinity correlates with cryptogein concentrations required for biological activity in vivo.
Comparison of the effects of cryptogein and oligogalacturonides on tabacco cells and evidence of different forms of desensitization induced by these …
1998
Abstract The effects of cryptogein and oligogalacturonides (OGs) were compared on tobacco cells by measuring calcium influx and calcium-dependent responses including extracellular alkalinization and H 2 O 2 production. The main difference is the higher calcium influx and the sustained H 2 O 2 production induced by cryptogein compared to OGs. Amplitude and duration of calcium signalling triggered by cryptogein or OGs may explain the necrotic effect of cryptogein, and the absence of necrosis in tobacco plants treated with OGs. We used induction of alkalinization and H 2 O 2 production to investigate cryptogein effects after a first treatment with cryptogein or OGs, and reciprocally. Results s…
Crocodile egg sounds signal hatching time.
2008
Summary Crocodilians are known to vocalize within the egg shortly before hatching [1,2]. Although a possible function of these calls — inducing hatching in siblings and stimulating the adult female to open the nest — has already been suggested, it has never been experimentally tested [1–5]. Here, we present the first experimental evidence that pre-hatching calls of Nile crocodile ( Crocodylus niloticus ) juveniles are informative acoustic signals which indeed target both siblings and mother.
DNA polymorphism at the FRIGIDA gene in Arabidopsis thaliana : extensive nonsynonymous variation is consistent with local selection for flowering time
2002
FRIGIDA (FRI) is a major gene involved in the regulation of flowering time in Arabidopsis thaliana. Nucleotide variation at this gene was investigated by sequencing 25 field ecotypes collected from western Europe. Genetic diversity at FRI was characterized by a high number of haplotypes and an excess of low-frequency polymorphisms. A large excess of intraspecific nonsynonymous variation associated with low synonymous variation was detected along the first exon in the FRI gene. In contrast, no excess of nonsynonymous divergence was detected between A. thaliana and A. lyrata. The Tajima and McDonald and Kreitman tests, however, suggested that this gene has evolved in a nonneutral fashion. Non…
Gene expression levels influence amino acid usage and evolutionary rates in endosymbiotic bacteria
2005
International audience; Most endosymbiotic bacteria have extremely reduced genomes, accelerated evolutionary rates, and strong AT base compositional bias thought to reflect reduced efficacy of selection and increased mutational pressure. Here, we present a comparative study of evolutionary forces shaping five fully sequenced bacterial endosymbionts of insects. The results of this study were three-fold: (i) Stronger conservation of high expression genes at not just nonsynonymous, but also synonymous, sites. (ii) Variation in amino acid usage strongly correlates with GC content and expression level of genes. This pattern is largely explained by greater conservation of high expression genes, l…
Nucleotide Variability at the Acetyl Coenzyme A Carboxylase Gene and the Signature of Herbicide Selection in the Grass Weed Alopecurus myosuroides (H…
2004
Acetyl coenzyme A carboxylase (ACCase) is the target of highly effective herbicides. We investigated the nucleotide variability of the ACCase gene in a sample of 18 black-grass (Alopecurus myosuroides [Huds.]) populations to search for the signature of herbicide selection. Sequencing 3,396 bp encompassing ACCase herbicide-binding domain in 86 individuals revealed 92 polymorphisms, which formed 72 haplotypes. The ratio of nonsynonymous versus synonymous substitutions was very low, in agreement with ACCase being a vital metabolic enzyme. Within black grass, most nonsynonymous substitutions were related to resistance to ACCase-inhibiting herbicides. Differentiation between populations was stro…
Can Deliberately Incomplete Gene Sample Augmentation Improve a Phylogeny Estimate for the Advanced Moths and Butterflies (Hexapoda: Lepidoptera)?
2011
Abstract This paper addresses the question of whether one can economically improve the robustness of a molecular phylogeny estimate by increasing gene sampling in only a subset of taxa, without having the analysis invalidated by artifacts arising from large blocks of missing data. Our case study stems from an ongoing effort to resolve poorly understood deeper relationships in the large clade Ditrysia ( > 150,000 species) of the insect order Lepidoptera (butterflies and moths). Seeking to remedy the overall weak support for deeper divergences in an initial study based on five nuclear genes (6.6 kb) in 123 exemplars, we nearly tripled the total gene sample (to 26 genes, 18.4 kb) but only in a…
Numerical response of predators to large variations of grassland vole abundance and long‐term community changes
2020
Abstract Voles can reach high densities with multiannual population fluctuations of large amplitude, and they are at the base of predator communities in Northern Eurasia and Northern America. This status places them at the heart of management conflicts wherein crop protection and health concerns are often raised against conservation issues. Here, a 20‐year survey describes the effects of large variations in grassland vole populations on the densities and the daily theoretical food intakes (TFI) of vole predators based on roadside counts. Our results show how the predator community responded to prey variations of large amplitude and how it reorganized with the increase in a dominant predator…
Use of microbial biostimulants to increase the salinity tolerance of vegetable transplants
2021
Vegetable plants are more sensitive to salt stress during the early growth stages