Monogalactosyldiacylglycerol and digalactosyldiacylglycerol deficiency disturbs the spatial arrangement of the thylakoid network leading to a decreased photosynthetic efficiency.
In chloroplasts of land plants, the thylakoid network is organized into appressed regions called grana stacks and loosely arranged parallel stroma thylakoids. Many factors determining such intricate structural arrangements have been identified so far, including various thylakoid-embedded proteins, and polar lipids that build the thylakoid matrix. Although carotenoids are important components of proteins and the lipid phase of chloroplast membranes, their role in determining the thylakoid network structure remains elusive. We studied 2D and 3D thylakoid network organization in carotenoid-deficient mutants (ccr1-1, lut5-1, szl1-1, and szl1-1npq1-2) of Arabidopsis (Arabidopsis thaliana) to reveal the structural role of carotenoids in the formation and dynamics of the internal chloroplast membrane system. The most significant structural aberrations took place in chloroplasts of the szl1-1 and szl1-1npq1-2 plants. Increased lutein/carotene ratio in these mutants impaired the formation of grana, resulting in a significant decrease in the number of thylakoids used to build a particular stack. Further, combined biochemical and biophysical analyses revealed that hampered grana folding was related to decreased thylakoid membrane fluidity and significant changes in the amount, organization, and phosphorylation status of photosystem (PS) II (PSII) supercomplexes in the szl1-1 and szl1-1npq1-2 plants. Such changes resulted from a synergistic effect of lutein overaccumulation in the lipid matrix and a decreased level of carotenes bound with PS core complexes. Moreover, more rigid membrane in the lutein overaccumulating plants led to binding of Rubisco to the thylakoid surface, additionally providing steric hindrance for the dynamic changes in the level of membrane folding.
Introduction: Ultrasound imaging is a safe, repeatable and easily available imaging procedure. Based on these qualities, it may become a useful tool for skin assessment in newborns. Aims: The aim of the study was to evaluate the usefulness of high-frequency ultrasound imaging for neonatal skin assessment. Another aim was to identify differences in ultrasound features of the skin in newborns depending on the examination site, sex, age, birth weight, and arterial blood gas results. Material and method: A total of 72 newborns in the first 24 hours of life, without any skin lesions, were included in the study. All newborns underwent ultrasound skin examinations in three body sites (forearm, abdomen and thigh) during the first 24 hours of life. DermaMed Ultrasound Scanner with a 48 MHz probe was used for imaging. A total of three structures were identified in the ultrasound images: epidermal echo, dermis, and subcutaneous tissue. The study assessed the thickness of the epidermis and dermis, and the echogenicity of the dermis and subcutaneous tissue. Data were analysed to determine possible links with sex, post-conceptional age, body weight, birth route, and results of umbilical cord blood gas analysis. Results: Depending on the body site examined, the mean epidermal thickness was 0.081 to 0.083 mm, while the mean thickness of the dermis ranged between 0.679 and 0.722 mm. The newborns with higher birth weights were shown to have a thicker epidermis regardless of the examined site [R (correlation coefficient) for the forearm: 0.47 (p <0.001), abdomen: 0.53 (p <0.001), thigh: 0.48 (p <0.001)]. A positive correlation was found between epidermal and dermal thickness (R = 0.34; p = 0.004), but a comparison of the three examined sites revealed no significant differences in the thickness of the two structures. The sex of the newborn had no significant effect on the ultrasound features of the skin. None of the ultrasound parameters under study was found to correlate with the pH level in umbilical cord blood gas analysis. Subcutaneous oedema was detected in the examined sites in all the newborns studied. Conclusions: High-frequency ultrasound imaging may become a useful method for neonatal skin assessment, complementing existing diagnostic techniques for monitoring pathologically altered skin.
Background Non-invasive alternatives to percutaneous renal biopsy are sought for follow-up of renal allografts. Purpose To evaluate the feasibility of intravoxel incoherent motion (IVIM) imaging in monitoring and predicting the function of renal allografts. Material and Methods Thirty-five kidney recipients were examined on a 1.5-T MR unit approximately three and 18 months after transplantation. Based on estimated glomerular filtration rate (eGFR), patients were divided into three groups: improved; declined; and stable graft function. Diffusion parameters were calculated with the use of monoexponential (total apparent diffusion coefficient [ADCT]) and biexponential (pure diffusion coefficient [D], perfusion fraction [Fp]) model and compared among and within study groups using Kruskal–Wallis, Mann–Whitney, and Wilcoxon matched pairs tests. Diffusion parameters were correlated with eGFR using Spearman’s rank correlation coefficients. Results of tests with P values < 0.05 were considered statistically significant. Results Values of diffusion parameters, especially Fp, were lower in patients with a declined graft function; however, statistically significant intergroup differences were observed only in a limited number of parameters at the time of follow-up magnetic resonance imaging (MRI). None of the diffusion parameters from the baseline MRI correlated with the change in eGFR over time. Flow-related diffusion parameters calculated with the IVIM model showed high variability. Conclusion We observed a trend toward a decrease in values of diffusion parameters in patients with a declined graft function. Further research is needed to verify a clinical usefulness of this observation.
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