Effect of Different Broad Waveband Lights on Membrane Lipids of a Cyanobacterium, Synechococcus sp., as Determined by UPLC-QToF-MS and Vibrational Spectroscopy

Characterization of monogalactosyldiacylglycerol synthases in Gracilariopsis lemaneiformis and their potential roles in the fading of the thallus

Membrane lipids play essential roles in regulating physiological properties in higher plants and algae. Monogalactosyldiacylglycerol (MGDG) is a major thylakoid membrane lipid, and it is an important source of polyunsaturated fatty acids for cells, plays a key role in the biogenesis of plastids, and maintains the function of the photosynthetic machinery. Several studies have indicated that the knockdown of MGDG synthase results in membrane lipid remodeling, albino seedlings, and changes in photosynthetic performance. However, the effects of MGDG synthase (MGD) inhibitors on lipids in macroalgae have not yet been clarified. Here, we characterized the effects of MGD inhibitors (ortho-phenanthroline and N-ethylmaleimide) on the composition of the fatty acids observed in MGDG and digalactosyldiacylglycerol (DGDG) in Gracilariopsis lemaneiformis using electrospray ionization-mass spectrometry. The most abundant MGDG species contained 16:0/18:1 (sn-1/sn-2) fatty acids, and the most dominant DGDG species contained 20:5/16:0 (sn-1/sn-2) fatty acids. Measurements of photosynthetic pigments and photosynthetic parameters revealed that photosynthesis of G. lemaneiformis was impaired. Principal component analysis and Spearman's correlation analysis revealed interactions between specific MGDG structural composition patterns and key metabolites involved in photosynthesis, indicating that 20:4/16:0 (sn-1/sn-2) MGDG and 16:0/18:1 (sn-1/sn-2) MGDG affect the structure and function of phycobilisomes and thus the color of G. lemaneiformis. Three genes (GlMGD1, GlMGD2, and GlMGD3) were cloned and identified. The addition of N-ethylmaleimide to G. lemaneiformis did not affect the abundance of GlMGD mRNA, and the abundance of transcripts was significantly decreased by ortho-phenanthroline.

Genome-Wide Characterization and Analysis of the bHLH Transcription Factor Family in Suaeda aralocaspica, an Annual Halophyte With Single-Cell C4 Anatomy

Basic helix-loop-helix (bHLH) transcription factors play important roles in plant growth, development, metabolism, hormone signaling pathways, and responses to abiotic stresses. However, comprehensive genomic and functional analyses of bHLH genes have not yet been reported in desert euhalophytes. Suaeda aralocaspica, an annual C4 halophyte without Kranz anatomy, presents high photosynthetic efficiency in harsh natural habitats and is an ideal plant for identifying transcription factors involved in stress resistance. In this study, 83 bHLH genes in S. aralocaspica were identified and categorized into 21 subfamilies based on conserved motifs, gene structures, and phylogenetic analysis. Functional annotation enrichment revealed that the majority of SabHLHs were enriched in Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways involved in the response to stress conditions, as transcription factors. A number of cis-acting elements related to plant hormones and stress responses were also predicted in the promoter regions of SabHLHs, which were confirmed by expression analysis under various abiotic stress conditions (NaCl, mannitol, low temperature, ABA, GA3, MeJA, and SA); most were involved in tolerance to drought and salinity. SabHLH169 (076) protein localized in the nucleus was involved in transcriptional activity, and gene expression could be affected by different light qualities. This study is the first comprehensive analysis of the bHLH gene family in S. aralocaspica. These data will facilitate further characterization of their molecular functions in the adaptation of desert plants to abiotic stress.

Differential Membrane Lipid Profiles and Vibrational Spectra of Three Edaphic Algae and One Cyanobacterium

The membrane glycerolipids of four phototrophs that were isolated from an edaphic assemblage were determined by UPLC-MS after cultivation in a laboratory growth chamber. Identification was carried out by 18S and 16S rDNA sequencing. The algal species were Klebsormidium flaccidum (Charophyta), Oocystis sp. (Chlorophyta), and Haslea spicula (Bacillariophyta), and the cyanobacterium was Microcoleus vaginatus (Cyanobacteria). The glycerolipid profile of Oocystis sp. was dominated by monogalactosyldiacylglycerol (MGDG) species, with MGDG(18:3/16:4) accounting for 68.6%, whereas MGDG(18:3/16:3) was the most abundant glycerolipid in K. flaccidum (50.1%). A ratio of digalactosyldiacylglycerol (DGDG) species to MGDG species (DGDG/MGDG) was shown to be higher in K. flaccidum (0.26) than in Oocystis sp. (0.14). This ratio increased under high light (HL) as compared to low light (LL) in all the organisms, with its highest value being shown in cyanobacterium (0.38-0.58, LL-HL). High contents of eicosapentaenoic acid (EPA, C20:5) and hexadecenoic acid were observed in the glycerolipids of H. spicula. Similar Fourier transform infrared (FTIR) and Raman spectra were found for K. flaccidum and Oocystis sp. Specific bands at 1629.06 and 1582.78 cm-1 were shown by M. vaginatus in the Raman spectra. Conversely, specific bands in the FTIR spectrum were observed for H. spicula at 1143 and 1744 cm-1. The results of this study point out differences in the membrane lipid composition between species, which likely reflects their different morphology and evolutionary patterns.

Identification of new spectral signatures from hepatitis C virus infected human sera

Hepatitis C virus (HCV) infection is one of the leading causes of morbidity and mortality worldwide. Mortality linked with HCV infection can be lowered with effective and prompt diagnosis in early stages of infection. In this study potential of Raman spectroscopy to differentiate between healthy and HCV infected serum samples was investigated. Clear differences were observed in the Raman spectra of HCV infected and healthy sera samples. Using the analysis of variance (ANOVA) and t-test (p < 0.001) on Raman spectra of diseased and healthy samples, we observed eleven unique Raman bands at 676, 825, 853, 936, 1029, 1105, 1155, 1305, 1620, 1654 and 1757 cm^-1 associated with only HCV infected sera and have not been reported in earlier studies. In addition, six Raman bands at 556, 585, 716, 815, 1273 and 1142 cm^-1were observed in healthy sera only. Three Raman bands at 1330, 1526 and 1572 cm^-1 were observed in both type of samples but their intensity was drastically reduced in diseased samples. Various multivariate analysis techniques were employed to demonstrate the robustness of the results. We employed multivariate and unsupervised principal component analysis (PCA) in conjunction with supervised classification linear discriminant analysis (LDA), using ten-fold jackknife cross-validation, in order to develop effective diagnostic algorithm technique (PCA-LDA). Our PCA-LDA model yielded sufficient sensitivity and specificity i.e. correctly identified all infected samples included in this study. Ours results indicate that these unique Raman bands have the potential to be used as biomarkers for optical diagnosis of HCV infection.