The xanthophyll cycle in diatom Phaeodactylum tricornutum in response to light stress.

Chosen aspects of the functioning of diadinoxanthin cycle in a model diatom Phaeodactylum tricornutum grown under low light conditions (LL) and under high light conditions (HL), which cause activation of violaxanthin cycle, were examined. Heterogeneity of the kinetics of diadinoxanthin ↔ diatoxanthin conversions regulated by de-epoxidase/epoxidase enzymes was detected. Three different rates of diadinoxanthin de-epoxidation (τ > 20 min, 5 min > τ > 1.

Effectiveness of behaviour change techniques on lifestyle interventions of patients with a high risk of developing cardiovascular disease. Using a qualitative approach.

This study aimed to identify key active ingredients on the maintenance of behaviour change for lifestyle interventions of patients with a high risk of developing cardiovascular disease (CVD) who participated in a MOtiVational intErviewing InTervention (MOVE IT) randomised control trial (RCT). A process evaluation was carried out using focus groups. Twenty-six participants of the MOVE IT RCT were purposively recruited and split into six focus groups.

The oxidative stress in allelopathy: Participation of prenyllipid antioxidants in the response to juglone in Chlamydomonas reinhardtii.

Allelopathy is a phenomenon, where one species releases compounds able to inhibit the growth of other species. Juglone, 5-hydroxy-1,4-naphtoquinone, is an allelochemical produced by walnut trees. The main mode of juglone toxicity is the formation of semiquinone radicals, able to reduce O to superoxide.

Isolation and purification of all- diadinoxanthin and all- diatoxanthin from diatom .

Two diatom-specific carotenoids are engaged in the diadinoxanthin cycle, an important mechanism which protects these organisms against photoinhibition caused by absorption of excessive light energy. A high-performance and economical procedure of isolation and purification of diadinoxanthin and diatoxanthin from the marine diatom using a four-step procedure has been developed. It is based on the use of commonly available materials and does not require advanced technology.

Physiological characterization of Chlamydomonas reinhardtii acclimated to chronic stress induced by Ag, Cd, Cr, Cu and Hg ions.

Acclimation to heavy metal-induced stress is a complex phenomenon. Among the mechanisms of heavy metal toxicity, an important one is the ability to induce oxidative stress, so that the antioxidant response is crucial for providing tolerance to heavy metal ions. The effect of chronic stress induced by ions of five heavy metals, Ag, Cu, Cr (redox-active metals) Cd, Hg (nonredox-active metals) on the green microalga Chlamydomonas reinhardtii was examined at two levels - the biochemical (content of photosynthetic pigments and prenyllipid antioxidants, lipid peroxidation) and the physiological (growth rate, photosynthesis and respiration rates, induction of nonphotochemical quenching of chlorophyll fluorescence).

Photosynthetic Pigments in Diatoms.

Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants.

Temperature effect on growth, and selected parameters of Phaeodactylum tricornutum in batch cultures.

The effect of optimal and stress temperatures on the growth kinetics of the Phaeodactylum tricornutum CCAP/1055/1 strain (a model diatom with a known genome sequence) in batch cultures was examined. The analysis of the obtained results showed two phases of culture growth. There were significant positive correlations between OD increase of chlorophyll a chlorophyll c and protein concentration at different temperatures.

Expression of three diadinoxanthin de-epoxidase genes of Phaeodacylum tricornutum in Escherichia coli Origami b and BL21 strain.

In the diadinoxanthin cycle the epoxy group is removed from diadinoxanthin and diatoxanthin is created. This conversion takes place e.g.

Zeaxanthin epoxidation - an in vitro approach.

Zeaxanthin epoxidase (ZE) is an enzyme operating in the violaxanthin cycle, which is involved in photoprotective mechanisms. In this work model systems to study zeaxanthin (Zx) epoxidation were developed. Two assay systems are presented in which epoxidation of Zx was observed.

Xanthophyll cycle--a mechanism protecting plants against oxidative stress.

Six different xanthophyll cycles have been described in photosynthetic organisms. All of them protect the photosynthetic apparatus from photodamage caused by light-induced oxidative stress. Overexcitation conditions lead, in the chloroplast, to the over-reduction of the NADP pool and production of superoxide, which can subsequently be metabolized to hydrogen peroxide or a hydroxyl radical, other reactive oxygen species (ROS).