Tocopherol and plastoquinone synthesis in spinach chloroplasts subfractions

Subfractions isolated from intact purified spinach chloroplasts are able to prenylate the aromatic moiety of α-tocopherol and plastoquinone-9 precursors. The biosynthesis of α-tocopherol and plastoquinone-9 is a compartmentalized process. The chloroplast envelope membranes are the only site of the enzymatic prenylation in α-tocopherol synthesis whereas the thylakoid membrane is also involved in the prenylation and methylation sequence of plastoquinone-9 biosynthesis. A very active kinase which forms phytyl-PP is localized in the stroma. Phytol but not geranylgeraniol is the polyprenol precursor of the side chain of α-tocopherol in spinach chloroplasts.     

Stomatal density in Pinus sylvestris as an indicator of temperature rather than CO2: Evidence from a pan-European transect

The commonly observed negative relationship between stomatal density (SD) and atmospheric CO₂ has led to SD being proposed as an indicator of atmospheric CO₂ concentration. The use of SD as a proxy for CO₂, however, has been hampered by an insufficient understanding of the intraspecific variation of this trait. We hypothesized that SD in Pinus sylvestris, a widely distributed conifer, varies geographically and that this variation is determined by major climatic variables. By sampling needles from naturally growing trees along a latitudinal range of 32.25°, equivalent to 13.7°C gradient of mean annual temperature (MAT) across Europe, we found that SD decreased from the warmest southern sites to the coldest sites in the north at a rate of 4 stomata per mm² for each 1°C, with MAT explaining 44% of the variation. Additionally, samples from a provenance trial exhibited a positive relationship between SD and the MAT of the original localities, suggesting that high SD is an adaptation to warm temperature. Our study revealed one of the strongest intraspecific relationships between SD and climate in any woody species, supporting the utility of SD as a temperature, rather than direct CO₂, proxy. In addition, our results predict the response of SD to climate warming.     

Spruce versus Arabidopsis: different strategies of photosynthetic acclimation to light intensity change

Photosynthesis Research - The acclimation of higher plants to different light intensities is associated with a reorganization of the photosynthetic apparatus. These modifications, namely, changes...     

Genotyping-by-sequencing performance in selected livestock species

Application of next generation sequencing for large scale genotyping in livestock is limited by high costs and challenging data analysis process. However, available restriction enzyme-based enrichment techniques like e.g. genotyping-by-sequencing (GBS) are promising tools allowing reduction of financial outlies by a high sample multiplexing and narrowing down the sequenced genome areas to the randomly distributed read tags. In this study, we tested the performance of standard, PstI endonuclease-adapted GBS protocol for population genetics in cattle, horse and sheep with application of different, including low-depth sequencing setups. It was found that the detected SNPs display desirable polymorphism parameters and are evenly scattered across the whole genome including gene coding regions. It was also shown that the SNPs can be successfully applied in population genetics, revealing the genetic differentiation of the studied breeds. The GBS approach represents a cost-effective alternative to existing genotyping methods which may find adoption in various research applications.     

Spectroscopic evaluation of synthesized 5β-dihydrocortisol and 5β-dihydrocortisol acetate binding mechanism with human serum albumin and their role in anticancer activity

Our study focus on the biological importance of synthesized 5β-dihydrocortisol (Dhc) and 5β-dihydrocortisol acetate (DhcA) molecules, the cytotoxic study was performed on breast cancer cell line (MCF-7) normal human embryonic kidney cell line (HEK293), the IC₅₀ values for MCF-7 cells were 28 and 25 μM, respectively, whereas no toxicity in terms of cell viability was observed with HEK293 cell line. Further experiment proved that Dhc and DhcA induced 35.6 and 37.7% early apoptotic cells and 2.5, 2.9% late apoptotic cells, respectively, morphological observation of cell death through TUNEL assay revealed that Dhc and DhcA induced apoptosis in MCF-7 cells. The complexes of HSA–Dhc and HSA–DhcA were observed as static quenching, and the binding constants (K) was 4.7 ± .03 × 10⁴ M^?1 and 3.9 ± .05 × 10⁴ M^?1_, and their binding free energies were found to be ?6.4 and ?6.16 kcal/mol, respectively. The displacement studies confirmed that lidocaine 1.4 ± .05 × 10⁴ M^?1 replaced Dhc, and phenylbutazone 1.5 ± .05 × 10⁴ M^?1 replaced by DhcA, which explains domain I and domain II are the binding sites for Dhc and DhcA. Further, FT-IR, synchronous spectroscopy, and CD results revealed that the secondary structure of HSA was altered in the presence of Dhc and DhcA. Furthermore, the atomic force microscopy and transmission electron microscopy showed that the dimensions like height and molecular size of the HSA–Dhc and HSA–DhcA complex were larger compared to HSA alone. Detailed analysis through molecular dynamics simulations also supported greater stability of HSA–Dhc and HSA–DhcA complexes, and root-mean-square-fluctuation interpreted the binding site of Dhc as domain IB and domain IIA for DhcA. This information is valuable for further development of steroid derivative with improved pharmacological significance as novel anti-cancer drugs.     

Evolution of the visual sensory system in cichlid fishes from crater lake Barombi Mbo in Cameroon

In deep‐water animals, the visual sensory system is often challenged by the dim‐light environment. Here, we focus on the molecular mechanisms involved in rapid deep‐water adaptations. We examined visual system evolution in a small‐scale yet phenotypically and ecologically diverse adaptive radiation, the species flock of cichlid fishes in deep crater lake Barombi Mbo in Cameroon, West Africa. We show that rapid adaptations of the visual system to the novel deep‐water habitat primarily occurred at the level of gene expression changes rather than through nucleotide mutations, which is compatible with the young age of the radiation. Based on retinal bulk RNA sequencing of all eleven species, we found that the opsin gene expression pattern was substantially different for the deep‐water species. The nine shallow‐water species feature an opsin palette dominated by the red‐sensitive (LWS) opsin, whereas the two unrelated deep‐water species lack expression of LWS and the violet‐sensitive (SWS2B) opsin, thereby shifting the cone sensitivity to the centre of the light spectrum. Deep‐water species further predominantly express the green‐sensitive RH2Aα over RH2Aβ. We identified one amino acid substitution in the RH2Aα opsin specific to the deep‐water species. We finally performed a comparative gene expression analysis in retinal tissue of deep‐ vs. shallow‐water species. We thus identified 46 differentially expressed genes, many of which are associated with functions in vision, hypoxia management or circadian clock regulation, with some of them being associated with human eye diseases.     

HPLC columns partition by chemometric methods based on peptides retention

In recent years, multivariate techniques have been utilized to evaluate reversed-phase high-performance liquid chromatographic data. In the present study, 11 high-performance liquid chromatography (HPLC) columns were divided into several groups according to the retention factors of 12 peptides. Principal component analysis (PCA) and cluster analysis (CA) were used in column and peptides' comparison and grouping. CA results indicated that all stationary phases may be generally grouped into several clusters, due to stationary phase structure and properties. On the other hand, interesting results were obtained with the use of PC. There is almost linear relationship between classified HPLC columns in the space of new PCs, which is connected with meaning of the PC's reflected in their loading values. The first component describes non-polar properties of peptides, whereas the second component is loaded with polar peptides having much lower logP values. PCA and CA were also used in peptides comparison however, complete explanation of peptides grouping still remains unclear.