Search results for "Cause"

Food limitation constrains host immune responses to nematode infections.

2016

Trade-offs in the allocation of finite-energy resources among immunological defences and other physiological processes are believed to influence infection risk and disease severity in food-limited wildlife populations. However, this prediction has received little experimental investigation. Here we test the hypothesis that food limitation impairs the ability of wild field voles ( Microtus agrestis ) to mount an immune response against parasite infections. We conducted a replicated experiment on vole populations maintained in large outdoor enclosures during boreal winter, using food supplementation and anthelmintic treatment of intestinal nematodes. Innate immune responses against intestina…

Changes in lipid and carotenoid metabolism in Chlamydomonas reinhardtii during induction of CO2-concentrating mechanism: Cellular response to low CO2…

2020

Photosynthetic organisms strictly depend on CO2 availability and the CO2:O2 ratio, as both CO2/O2 compete for catalytic site of Rubisco. Green alga Chlamydomonas reinhardtii, can overcome CO2 shortage by inducing CO2-concentrating mechanism (CCM). Cells transferred to low-CO2 are subjected to light-driven oxidative stress due to decrease in the electron sink. Response to environmental perturbations is mediated to some extent by changes in the lipid and carotenoid metabolism. We thus hypothesize that when cells are challenged with changes in CO2 availability, changes in the lipidome and carotenoids profile occur. These changes expected to be transient, when CCM is activated, CO2 limitation w…

Extraction and Analysis of Carotenoids from Escherichia coli in Color Complementation Assays

2017

A common method to investigate the function of genes putatively involved in carotenoid biosynthesis is the so called color complementation assay in Escherichia coli (see, e.g., Cunningham and Gantt, 2007). In this assay, the gene under investigation is expressed in E. coli strains genetically engineered to synthesize potential carotenoid substrates, followed by analysis of the pigment changes in the carotenogenic bacteria via high-performance liquid chromatography (HPLC). Two crucial steps in this method are (i) the quantitative extraction of the carotenoids out of E. coli and (ii) the reproducible and complete separation of the pigments by HPLC. Here, we present a protocol for the extracti…

Biotechnological Applications for the Sustainable Use of Marine By-products: In Vitro Antioxidant and Pro-apoptotic Effects of Astaxanthin Extracted …

2019

In this study, the carotenoid astaxanthin was obtained by supercritical fluid extraction (SFE) from shrimp by-products (SBP). Its bioactive properties were evaluated in vitro in human normal and cancerous cells lines. The antioxidant activity of the extracted astaxanthin of the SFE fraction (ASTA) was tested in fibroblast cells (HS-68), by inducing oxidative stress and by evaluating the protective effect of the pre-treatment with different levels of ASTA against toxicity. The anti-proliferative activity was evaluated in hepatoma cells (HEP-G2), treated with increased concentrations of ASTA and measuring the effects on vitality and on some biomolecular markers related to oxidative stress, ce…

Dehydration rate determines the degree of membrane damage and desiccation tolerance in bryophytes.

2016

Desiccation tolerant (DT) organisms are able to withstand an extended loss of body water and rapidly resume metabolism upon rehydration. This ability, however, is strongly dependent on a slow dehydration rate. Fast dehydration affects membrane integrity leading to intracellular solute leakage upon rehydration and thereby impairs metabolism recovery. We test the hypothesis that the increased cell membrane damage and membrane permeability observed under fast dehydration, compared with slow dehydration, is related to an increase in lipid peroxidation. Our results reject this hypothesis because following rehydration lipid peroxidation remains unaltered, a fact that could be due to the high incr…

Kineococcus vitellinus sp. nov., Kineococcus indalonis sp. nov. and Kineococcus siccus sp. nov., isolated nearby the Tabernas desert (Almería, Spain)

2020

This article belongs to the Section Environmental Microbiology.

2016

Several insect taxa are associated with intracellular symbionts that provision limiting nutrients to their hosts. Such tightly integrated symbioses are especially common in insects feeding on nutritionally challenging diets like phloem sap or vertebrate blood, but also occur in seed-eating and omnivorous taxa. Here, we characterize an intracellular symbiosis in pollen-feeding beetles of the genus Dasytes (Coleoptera, Dasytidae). High-throughput tag-encoded 16S amplicon pyrosequencing of adult D. plumbeus and D. virens revealed a single gamma-proteobacterial symbiont that amounts to 52.4-98.7% of the adult beetles’ entire microbial community. Almost complete 16S rRNA sequences phylogenetical…

Responses of marine mussel Mytilus galloprovincialis (Bivalvia: Mytilidae) after infection with the pathogen Vibrio splendidus

2019

International audience; Bivalve molluscs possess effective cellular and humoral defence mechanisms against bacterial infection. Although the immune responses of mussels to challenge with pathogenic vibrios have been largely investigated, the effects at the site of injection at the tissue level have not been so far evaluated. To this aim, mussels Mytilus galloprovincialis were herein in vivo challenged with Vibrio splendidus to assess the responses induced in hemolymph and posterior adductor muscle (PAM), being the site of bacterial infection. The number of living intra-hemocyte bacteria increased after the first hour post-injection (p.i.), suggesting the occurrence of an intense phagocytosi…

An Arabidopsis Mutant Over-Expressing Subtilase SBT4.13 Uncovers the Role of Oxidative Stress in the Inhibition of Growth by Intracellular Acidificat…

2020

Intracellular acid stress inhibits plant growth by unknown mechanisms and it occurs in acidic soils and as consequence of other stresses. In order to identify mechanisms of acid toxicity, we screened activation-tagging lines of Arabidopsis thaliana for tolerance to intracellular acidification induced by organic acids. A dominant mutant, sbt4.13-1D, was isolated twice and shown to over-express subtilase SBT4.13, a protease secreted into endoplasmic reticulum. Activity measurements and immuno-detection indicate that the mutant contains less plasma membrane H+-ATPase (PMA) than wild type, explaining the small size, electrical depolarization and decreased cytosolic pH of the mutant but not orga…

Females pay the oxidative cost of dominance in a highly social bird.

2018

12 pages; International audience; Understanding the evolution and maintenance of social behaviour requires a better understanding of the physiological mechanisms underlying the trade-offs between the benefits and costs of social status. Social dominance is expected to provide advantages in terms of access to resources and to reproduction but acquiring and maintaining dominance may also entail physiological costs. Dominant individuals are likely to engage more frequently in aggressive behaviours and/or may allocate a substantial amount of energy and resources to signal their status. Hence, dominance is likely to involve multiple physiological processes that stimulate aerobic metabolism and l…