Impaired photosystem I oxidation induces STN7-dependent phosphorylation of the light-harvesting complex I protein Lhca4 in Arabidopsis thaliana

Reduction of the plastoquinone (PQ) pool is known to activate phosphorylation of thylakoid proteins. In the Arabidopsis thaliana mutants psad1-1 and psae1-3, oxidation of photosystem I (PSI) is impaired, and the PQ pool is correspondingly over-reduced. We show here that, under these conditions, the antenna protein Lhca4 of PSI becomes a target for phosphorylation. Phosphorylation of the mature Lhca4 protein at Thr16 is suppressed in stn7 psad1 and stn7 psae1 double mutants. Thus, under extreme redox conditions, hyperactivation of thylakoid protein kinases and/or reorganization of thylakoid protein complex distribution increase the susceptibility of PSI to phosphorylation

A microjet based recuperator for application in domestic micro chp

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.In the paper the original design of a compact heat exchanger with microjets producing intensification effect is presented. Its primary application is for the domestic Organic Rankine Cycle (ORC), however, the design is universal and may have numerous other applications. The technology of microjets manufacturing is an “in-house” patented design. In the present paper the idea of such a heat exchanger is shown together with the flow and thermal characteristics of the prototype. The developed prototype of heat exchanger is capable of exchanging 5 kW of thermal energy at a logarithmic mean temperature difference (LMTD) of 60 K. The total heat transfer surface equal to 0.0072 m2 leads to very significant heat fluxes. Measured overall heat transfer coefficient reaches 12000 W/m2K, which was calculated using the Wilson method. The description of the Wilson technique used for the determination of the heat transfer coefficient is also presented in the body of the text. That method seems to be, in the authors’ opinion, the only one for finding the heat transfer coefficient for such a complex heat exchanger structure. In this case measurements of wall temperatures are not possible and hence the determination of heat transfer coefficient is difficult. The results of performed measurements are satisfactory and encourage for further research of the original design.pm201

Systems-wide analysis of manganese deficiency-induced changes in gene activity of Arabidopsis roots

Manganese (Mn) is pivotal for plant growth and development, but little information is available regarding the strategies that evolved to improve Mn acquisition and cellular homeostasis of Mn. Using an integrated RNA-based transcriptomic and high-throughput shotgun proteomics approach, we generated a comprehensive inventory of transcripts and proteins that showed altered abundance in response to Mn deficiency in roots of the model plant Arabidopsis. A suite of 22,385 transcripts was consistently detected in three RNA-seq runs; LC-MS/MS-based iTRAQ proteomics allowed the unambiguous determination of 11,606 proteins. While high concordance between mRNA and protein expression (R = 0.87) was observed for transcript/protein pairs in which both gene products accumulated differentially upon Mn deficiency, only approximately 10% of the total alterations in the abundance of proteins could be attributed to transcription, indicating a large impact of protein-level regulation. Differentially expressed genes spanned a wide range of biological functions, including the maturation, translation, and transport of mRNAs, as well as primary and secondary metabolic processes. Metabolic analysis by UPLC-qTOF-MS revealed that the steady-state levels of several major glucosinolates were significantly altered upon Mn deficiency in both roots and leaves, possibly as a compensation for increased pathogen susceptibility under conditions of Mn deficiency

Role of Plastid Protein Phosphatase TAP38 in LHCII Dephosphorylation and Thylakoid Electron Flow

Regulation of photosynthesis efficiency involves reversible phosphorylation of the light-harvesting complex through the activity of the newly identified phosphatase TAP38

The importance of nutritional factors and dietary management of Hashimoto’s thyroiditis

Hashimoto (HT) is an autoimmune disease in which destruction of the thyroid occurs as a result of lymphocyte infiltration. It is caused by an increased level of titers of antibody against thyroid peroxidase (TPO) and thyroglobulin (TG). Because of that, in HT patients, changes are observed in the level and metabolism of thyroid hormones, which leads to unspecified physical and psychological symptoms. A high level of antibodies attacking thyroid antigens has been positively correlated with the symptoms. From the etiological point of view, the most important are genetic factors; however, environmental factors are necessary to provoke the immune system to attack until the process is over. Scientists indicate specified stress, toxification, microbiota dysbiosis and under- or over-nutrition, to name only a few. Dietotherapy of Hashimoto’s is based on the proper nourishment of the body and regulation of the immune system by an anti-inflammatory diet. Observational and controlled trials have shown frequent nutrition deficiencies in HT patients. In literature, there is evidence for selenium, potassium, iodine, copper, magnesium, zinc, iron, vitamin A, C, D and B. The role of the proper level of protein intake, dietary fibre and unsaturated fatty acids, especially the n-3 family, has been indicated. HT patients should often eliminate lactose because of intolerance and interactions with levothyroxine and gluten because of possible interactions of gliadin with thyroid antigens. The article describes the nutrition factors of HT patients, and share nutrition recommendations for diet therapy

Conserved histidine of metal transporter AtNRAMP1 is crucial for optimal plant growth under manganese deficiency at chilling temperatures

Manganese (Mn) is an essential nutrient required for plant growth, in particular in the process of photosynthesis. Plant performance is influenced by various environmental stresses including contrasting temperatures, light or nutrient deficiencies. The molecular responses of plants exposed to such stress factors in combination are largely unknown. Screening of 108 Arabidopsis thaliana (Arabidopsis) accessions for reduced photosynthetic performance at chilling temperatures was performed and one accession (Hog) was isolated. Using genetic and molecular approaches, the molecular basis of this particular response to temperature (GxE interaction) was identified. Hog showed an induction of a severe leaf chlorosis and impaired growth after transfer to lower temperatures. We demonstrated that this response was dependent on the nutrient content of the soil. Genetic mapping and complementation identified NRAMP1 as the causal gene. Chlorotic phenotype was associated with a histidine to tyrosine (H239Y) substitution in the allele of Hog NRAMP1. This led to lethality when Hog seedlings were directly grown at 4 degrees C. Chemical complementation and hydroponic culture experiments showed that Mn deficiency was the major cause of this GxE interaction. For the first time, the NRAMP-specific highly conserved histidine was shown to be crucial for plant performance

The PsbP Domain Protein 1 Functions in the Assembly of Lumenal Domains in Photosystem I

Photosystem I (PS I) is a multisubunit membrane protein complex that functions as a light-driven plastocyanin-ferredoxin oxidoreductase. The PsbP domain protein 1 (PPD1; At4g15510) is located in the thylakoid lumen of plant chloroplasts and is essential for photoautotrophy, functioning as a PS I assembly factor. In this work, RNAi was used to suppress PPD1 expression, yielding mutants displaying a range of phenotypes with respect to PS I accumulation and function. These PPD1 RNAi mutants showed a loss of assembled PS I that was correlated with loss of the PPD1 protein. In the most severely affected PPD1 RNAi lines, the accumulated PS I complexes exhibited defects in electron transfer from plastocyanin to the oxidized reaction center P(700)(+). The defects in PS I assembly in the PPD1 RNAi mutants also had secondary effects with respect to the association of light-harvesting antenna complexes to PS I. Because of the imbalance in photosystem function in the PPD1 RNAi mutants, light-harvesting complex II associated with and acted as an antenna for the PS I complexes. These results provide new evidence for the role of PPD1 in PS I biogenesis, particularly as a factor essential for proper assembly of the lumenal portion of the complex