Far-Red Light Coordinates the Diurnal Changes in the Transcripts Related to Nitrate Reduction, Glutathione Metabolism and Antioxidant Enzymes in Barley

Spectral quality, intensity and period of light modify many regulatory and stress signaling pathways in plants. Both nitrate and sulfate assimilations must be synchronized with photosynthesis, which ensures energy and reductants for these pathways. However, photosynthesis is also a source of reactive oxygen species, whose levels are controlled by glutathione and other antioxidants. In this study, we investigated the effect of supplemental far-red (735 nm) and blue (450 nm) lights on the diurnal expression of the genes related to photoreceptors, the circadian clock, nitrate reduction, glutathione metabolism and various antioxidants in barley. The maximum expression of the investigated four photoreceptor and three clock-associated genes during the light period was followed by the peaking of the transcripts of the three redox-responsive transcription factors during the dark phase, while most of the nitrate and sulfate reduction, glutathione metabolism and antioxidant-enzyme-related genes exhibited high expression during light exposure in plants grown in light/dark cycles for two days. These oscillations changed or disappeared in constant white light during the subsequent two days. Supplemental far-red light induced the activation of most of the studied genes, while supplemental blue light did not affect or inhibited them during light/dark cycles. However, in constant light, several genes exhibited greater expression in blue light than in white and far-red lights. Based on a correlation analysis of the gene expression data, we propose a major role of far-red light in the coordinated transcriptional adjustment of nitrate reduction, glutathione metabolism and antioxidant enzymes to changes of the light spectrum.

Light intensity and spectrum affect metabolism of glutathione and amino acids at transcriptional level

The effects of various light intensities and spectral compositions on glutathione and amino acid metabolism were compared in wheat. Increase of light intensity (low-normal-high) was accompanied by a simultaneous increase in the shoot fresh weight, photosynthetic activity and glutathione content. These parameters were also affected by the modification of the ratios of blue, red and far-red components (referred to as blue, pink and far-red lights) compared to normal white light. The photosynthetic activity and the glutathione content decreased to 50% and the percentage of glutathione disulfide (characterising the redox state of the tissues) in the total glutathione pool doubled in far-red light. The alterations in the level and redox state of the antioxidant glutathione resulted from the effect of light on its synthesis as it could be concluded from the changes in the transcription of the related genes. Modification of the light conditions also greatly affected both the amount and the ratio of free amino acids. The total free amino acid content was greatly induced by the increase of light intensity and was greatly reduced in pink light compared to the normal intensity white light. The concentrations of most amino acids were similarly affected by the light conditions as described for the total free amino acid content but Pro, Met, Thr, ornithine and cystathionine showed unique response to light. As observed for the amino acid levels, the expression of several genes involved in their metabolism also enhanced due to increased light intensity. Interestingly, the modification of the spectrum greatly inhibited the expression of most of these genes. Correlation analysis of the investigated parameters indicates that changes in the light conditions may affect growth through the adjustment of photosynthesis and the glutathione-dependent redox state of the tissues. This process modifies the metabolism of glutathione and amino acids at transcriptional level.

High tricellulin expression is associated with better survival in human hepatoblastoma

AIMS

The more differentiated fetal component of hepatoblastoma (HB) is characterized by increased expression of tight junction (TJ) proteins claudin-1 and -2 when compared with embryonal component. Expression patterns of the recently identified TJ protein tricellulin and the epigenetic regulator enzyme EZH2 were investigated in epithelial subtypes of HB and related to survival.

METHODS AND RESULTS

Twenty-one cases of epithelial HBs subtyped as pure fetal (n = 12) and embryonal/fetal (n = 9), along with 16 non-tumorous samples from surrounding liver, were analysed by immunohistochemistry for tricellulin, β-catenin and EZH2 expression. No significant differences were revealed in overall survival between fetal and embryonal/fetal types of HBs. The fetal component, however, showed considerably increased tricellulin expression while the embryonal component displayed significantly increased nuclear EZH2 positivity, in comparison to other epithelial subtypes and non-tumorous surrounding hepatocytes. Strong nuclear β-catenin staining was notably more frequent in embryonal than in fetal types. High tricellulin expression was associated with significantly increased overall survival (P = 0.03), while elevated EZH2 expression was linked to the presence of distant metastases (P = 0.013).

CONCLUSIONS

Our data indicate that patients with treated HBs showing high expression of tricellulin have significantly better overall survival, independent of histological subtype. Increased nuclear expression of EZH2 was associated with the presence of distant metastases.

MicroRNA expression might predict prognosis of epithelial hepatoblastoma

Hepatoblastoma (HB) is the most common primary liver cancer in childhood. The fetal and mixed embryonal/fetal epithelial subtypes of HB differ not only in grade of differentiation but probably also in prognosis. We aimed to determine microRNA (miRNA) expression patterns of the main subtypes of epithelial HBs to reveal differences and relate them to survival. We studied 20 cases of epithelial HB, subtyped as pure fetal (n = 12) or embryonal/fetal (n = 8). Tissues were sampled according to subtype to arrive at 15 purely fetal and eight purely embryonal samples (n = 8) and 15 samples of non-tumorous surrounding liver (SL). Relative expression of miR-17-5p, miR-18a, miR-21, miR-34a, miR-96, miR-122, miR-181a, miR-195, miR-210, miR-214, miR-221, miR-222, miR-223, and miR-224 was determined by TaqMan MicroRNA Assays applying miR-140 as reference. A higher level of miR-18a (p < 0.01) was found in embryonal samples than in fetal samples. Lower miR-17-5p, miR-195, miR-210, miR-214, and higher miR-221 levels were detected in fetal samples (p < 0.02) in comparison with SL samples, whereas a lower miR-122 level was observed in embryonal samples (p < 0.003). Histological subtype did not correlate with survival; however, high miR-21, low miR-222, and low miR-224 levels proved to be independently prognostic for HB with significantly increased overall survival (p < 0.03). The fetal and embryonal components of epithelial HB, as well as SL, revealed different miRNA expression patterns. Furthermore, miR-21, miR-222, and miR-224 levels predict overall survival of HB patients regardless of epithelial subtype.

Phylogenetic analysis of a nosocomial transmission of hepatitis B virus at a paediatric haematology ward

A nosocomial Hepatitis B virus (HBV) outbreak at a paediatric onco-haematology unit was investigated using molecular biological methods to determine the origin of the infections. The National Reference Laboratory of Hepatitis Viruses received seven HBsAg positive sera from patients and one from the brother of a patient. A fragment of the preS1/preS2/S genes from all samples was amplified, the PCR products were sequenced and a rooted phylogenetic tree was constructed. All nucleotide sequences from the different patients were very similar and 6 of the 8 sequences were identical, suggesting a common origin of the infections. These sequences were closely related to those amplified from a nosocomial HBV epidemic in another hospital in Hungary. The on-scene investigation revealed several malpractices. The two hospital departments had close connections and some of the patients were treated in both institutions. Present report underlines the importance of developing screening protocols for hepatitis viruses and that of the introduction of regular training programs for health care professionals in the field of hospital hygiene.