Search results for "classification"

Pearl grafting: tracking the biological origin of nuclei by straightforward immunological methods.

2018

9 pages; International audience; French Polynesia is renowned for the production of Tahitian black pearl. These gems are obtained by grafting a nucleus into the gonad of a receiving oyster together with a graft, i.e. a small section of mantle tissue of a donor oyster. This procedure initiates the formation of a pearl sack around the nucleus, and subsequently, the deposition of concentric layers of nacre. The nucleus plays a key-role in pearl formation and its characteristics influence markedly the quality of the final product. As it is manufactured from mollusc shells, it contains a small percentage of organics. In the present paper, we used a set of biochemical techniques to characterize a…

Divergent parasite infections in sympatric cichlid species in Lake Victoria

2018

Parasitism has been proposed as a factor in host speciation, as an agent affecting coexistence of host species in species-rich communities and as a driver of post-speciation diversification. Young adaptive radiations of closely related host species of varying ecological and genomic differentiation provide interesting opportunities to explore interactions between patterns of parasitism, divergence and coexistence of sympatric host species. Here, we explored patterns in ectoparasitism in a community of 16 fully sympatric cichlid species at Makobe Island in Lake Victoria, a model system of vertebrate adaptive radiation. We asked whether host niche, host abundance or host genetic differentiatio…

Biological control of potato soft rot caused by Dickeya solani and the survival of bacterial antagonists under cold storage conditions

2018

Dickeya and Pectobacterium are responsible for causing blackleg of plants and soft rot of tubers in storage and in the field, giving rise to losses in seed potato production. In an attempt to improve potato health, biocontrol activity of known and putative antagonists was screened using in vitro and in planta assays, followed by analysis of their persistence at various storage temperatures. Most antagonists had low survival on potato tuber surfaces at 4 °C. The population dynamics of the best low‐temperature tolerant strain and also the most efficient antagonist, Serratia plymuthica A30, along with Dickeya solani as target pathogen, was studied with TaqMan real‐time PCR throughout the stora…

Cultivar- and Wood Area-Dependent Metabolomic Fingerprints of Grapevine Infected by Botryosphaeria Dieback

2020

International audience; Botryosphaeria dieback is one of the most significant grapevine trunk diseases that affects the sustainability of the vineyards and provokes economic losses. The causal agents, Botryosphaeriaceae species, live in and colonize the wood of the perennial organs causing wood necrosis. Diseased vines show foliar symptoms, chlorosis, or apoplexy, associated to a characteristic brown stripe under the bark. According to the susceptibility of the cultivars, specific proteins such as PR-proteins and other defense-related proteins are accumulated in the brown stripe compared with the healthy woody tissues. In this study, we enhanced the characterization of the brown stripe and …

How ants acclimate: Impact of climatic conditions on the cuticular hydrocarbon profile

2017

1.Organisms from temperate zones are exposed to seasonal changes and must be able to cope with a wide range of climatic conditions. Especially ectotherms, including insects, are at risk to desiccate under dry and warm conditions, the more so given the changing climate. 2.To adjust to current conditions, organisms acclimate through changes in physiology, morphology and/or behaviour. Insects protect themselves against desiccation through a layer of cuticular hydrocarbons (CHC) on their body surface. Hence, acclimation may also affect the CHC profile, changing their waterproofing capacity under different climatic conditions. 3.Here, we investigated the acclimation response of two Temnothorax a…

Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways

2015

The red palm weevil (RPW; Rhynchophorus ferrugineus) is spreading worldwide and severely harming many palm species. However, most studies on RPW focused on insect biology, and little information is available about the plant response to the attack. In the present experiment, we used metabolomics to study the alteration of the leaf metabolome of Phoenix canariensis at initial (1st stage) or advanced (2nd stage) attack by RPW compared with healthy (unattacked) plants. The leaf metabolome significantly varied among treatments. At the 1st stage of attack, plants showed a reprogramming of carbohydrate and organic acid metabolism; in contrast, peptides and lipid metabolic pathways underwent more c…

Underestimated regional species diversity in the Cape Floristic Region revealed by phylogenetic analysis of the Erica abietina/E. viscaria clade (Eri…

2017

Synthesis of Isomaltooligosaccharides by Saccharomyces cerevisiae Cells Expressing Aspergillus niger α‑Glucosidase

2017

The α-glucosidase encoded by the aglA gene of Aspergillus niger is a secreted enzyme belonging to family 31 of glycoside hydrolases. This enzyme has a retaining mechanism of action and displays transglycosylating activity that makes it amenable to be used for the synthesis of isomaltooligosaccharides (IMOs). We have expressed the aglA gene in Saccharomyces cerevisiae under control of a galactose-inducible promoter. Recombinant yeast cells expressing the aglA gene produced extracellular α-glucosidase activity about half of which appeared cell bound whereas the other half was released into the culture medium. With maltose as the substrate, panose is the main transglycosylation product after 8…

Evidence for Succession and Putative Metabolic Roles of Fungi and Bacteria in the Farming Mutualism of the Ambrosia Beetle Xyleborus affinis.

2020

The bacterial and fungal community involved in ambrosia beetle fungiculture remains poorly studied compared to the famous fungus-farming ants and termites. Here we studied microbial community dynamics of laboratory nests, adults, and brood during the life cycle of the sugarcane shot hole borer, Xyleborus affinis. We identified a total of 40 fungal and 428 bacterial operational taxonomic units (OTUs), from which only five fungi (a Raffaelea fungus and four ascomycete yeasts) and four bacterial genera (Stenotrophomonas, Enterobacter, Burkholderia, and Ochrobactrum) can be considered the core community playing the most relevant symbiotic role. Both the fungal and bacterial populations varied s…

2020

During winter insects face energetic stress driven by lack of food, and thermal stress due to sub-optimal and even lethal temperatures. To survive, most insects living in seasonal environments such as high latitudes, enter diapause, a deep resting stage characterized by a cessation of development, metabolic suppression and increased stress tolerance. The current study explores physiological adaptations related to diapause in three beetle species at high latitudes in Europe. From an ecological perspective, the comparison is interesting since one species (Leptinotarsa decemlineata) is an invasive pest that has recently expanded its range into northern Europe, where a retardation in range expa…