The dirhodium-method in the determination of absolute configurations of phospholene chalcogenides

The 1H, 13C, and 31P NMR signals of six chiral phospholene chalcogenides (X = O, S, Se) are duplicated in the presence of one mole equivalent of the chiral auxiliary Rh2[(R)-MTPA]4 (diastereomeric dispersion Deltanu; in Hz). The samples were investigated as nonracemic mixtures of enantiomers with known absolute configurations so that signs can be attributed to the Deltanu-values and each signal set can be assigned to the respective enantiomer. The signs are uniform--in particular those of 1H nuclei--and nearly independent of the nature of the chalcogen atom. Thus, if the absolute configuration of one compound is known, it is possible to derive absolute configurations in the whole series (correlation method).     

Chromosome pairing in triploid intergeneric hybrids ofFestuca pratensis withLolium multiflorum, revealed by GISH

Genomic in situ hybridisation (GISH) was used to reveal chromosome pairing in two partly fertile, triploid (2n = 3x = 21) hybrids obtained by crossing the diploid (2n = 2x = 14) Festuca pratensis Huds. (designated FpFp), used as a female parent, with the autotetraploid (2n = 4x = 28) Lolium multiflorum Lam. (designated LmLmLmLm), used as a male parent. The pattern of chromosome pairing calculated on the basis of the mean values of chromosome configurations identified in all 100 PMCs analysed, was: 0.71I Lm + 2.24I Fp + 2.18II Lm/Lm + 0.54II Lm/Fp + 4.18III Lm/Lm/Fp. A relatively high number of Lm/Lm bivalents and Fp univalents, and a low number of Lm/Fp bivalents and Lm univalents indicated that the pairing was preferential between L. multiflorum chromosomes. Other observations regarding chromosome pairing within the Lm/Lm/Fp trivalents also confirmed this preferential pairing in the analysed triploids, as the Fp chromosome was not randomly located in the chain- and frying-pan-shaped trivalents. The similarities and differences in chromosome pairing at metaphase I and the level of preferential pairing between Lolium chromosomes in the different triploid Lolium-Festuca hybrids are discussed.     

Microbial transformations of flavanone and 6-hydroxyflavanone by Aspergillus niger strains

Flavanone (1) and 6-hydroxyflavanone (2) were subjected to transformation by means of Aspergillus niger strains (one wild and three UV mutants). For both substrates the biotransformation resulted in reduction of the carbonyl group (products 5 and 7) and dehydrogenation at C-2 and C-3 (3 and 8). Additionally, for flavanone (1) reduction of C-4 together with hydroxylation at C-7 (6) and dehydrogenation at C-2, C-3 along with hydroxylation at C-3 (4) were observed.     

Increased percentage of CD8+CD28- T cells correlates with clinical activity in primary Sjögren's syndrome

The role of CD28- T cell subpopulations in primary Sj?gren's syndrome (pSS) has become controversial. Changes in the number of CD28- T cells have been demonstrated in autoimmune diseases in co-existence with Sj?gren's syndrome. The study aimed to indicate differences in the number of CD4+CD28- and CD8+CD28- T cells in patients with sicca syndrome and suspected pSS. Thirty patients with sicca syndrome at baseline were studied and followed up for 5months. After final diagnosis, comparison was made of the previously recorded lymphocyte subpopulations in patients with pSS and those in other defined subgroups. Notably high percentages of CD8+CD28- T cells were indicated in pSS patients, which correlated with the severity of the sicca symptoms and cutaneous and muscular systemic disease activity. Changes in CD8+CD28- T cell percentages may thus assist in the early differential diagnosis of pSS patients from those with similar clinical symptoms.     

Changes in surface-charge density of blood cells after sudden unexpected death

The objective of the investigation was evaluation of postmortem changes of electric charge of human erythrocyte and thrombocyte membranes after sudden unexpected death. The surface charge density values were determined on the basis of the electrophoretic mobility measurements of the cells carried out at various pHs of electrolyte solution. The interactions between both erythrocyte and thrombocyte membranes and electrolyte ions were studied. Values of parameters characterizing the membrane--that is, the total surface concentrations of both acidic and basic groups and their association constants with solution ions--were calculated on the basis of a four-equilibria mathematical model. The model was validated by comparison of these values to experimental data. We established that examined electric properties of the cell membranes are affected by sudden unexpected death. Postmortem processes occurring in the cell membranes can lead to disorders of existing equilibria, which in turn result in changes in values of all the above-mentioned parameters.     

NITROGEN FIXATION,HYDROGEN CYCLING,AND ELECTRON TRANSPORT KINETICS IN TRICHODESMIUM ERYTHRAEUM (CYANOBACTERIA) STRAIN IMS1011

This study describes the relationships between dinitrogen (N₂) fixation, dihydrogen (H₂) production, and electron transport associated with photosynthesis and respiration in the marine cyanobacterium Trichodesmium erythraeum Ehrenb. strain IMS101. The ratio of H₂ produced:N₂ fixed (H₂:N₂) was controlled by the light intensity and by the light spectral composition and was affected by the growth irradiance level. For Trichodesmium cells grown at 50 μmol photons · m^?2 · s^?1, the rate of N₂ fixation, as measured by acetylene reduction, saturated at light intensities of 200 μmol photons · m^?2 · s^?1. In contrast, net H₂ production continued to increase with light levels up to 1,000 μmol photons · m^?2 · s^?1. The H₂:N₂ ratios increased monotonically with irradiance, and the variable fluorescence measured using a fast repetition rate fluorometer (FRRF) revealed that this increase was accompanied by a progressive reduction of the plastoquinone (PQ) pool. Additions of 2,5‐dibromo‐3‐methyl‐6‐isopropyl‐p‐benzoquinone (DBMIB), an inhibitor of electron transport from PQ pool to PSI, diminished both N₂ fixation and net H₂ production, while the H₂:N₂ ratio increased with increasing level of PQ pool reduction. In the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU), nitrogenase activity declined but could be prolonged by increasing the light intensity and by removing the oxygen supply. These results on the coupling of N₂ fixation and H₂ cycling in Trichodesmium indicate how light intensity and light spectral quality of the open ocean can influence the H₂:N₂ ratio and modulate net H₂ production.     

Influence of Incubation Conditions on Hydrolysis Efficiency and Iodine Enrichment in Baker’s Yeast

The influence of incubation conditions, enzyme type, hydrolysis time, and potassium iodide concentration on hydrolysis and iodine enrichment were studied in supernatant and pellets of Saccharomyces cervisiae hydrolysates. The type of enzyme used and incubation time significantly influence hydrolysis efficiency and protein concentration in supernatant and pellet. The highest protein hydrolysis efficiency was obtained by 24-h incubation with papain. Significantly lower values were observed for pepsin and autolysis. The potassium iodide concentration influences the iodine content of supernatant and pellet, but not hydrolysis. Iodide enrichment of supernatant and pellet depends on the concentration of iodide using during incubation. High concentration of iodide and long incubation times were the conditions for optimal iodide enrichment and high-protein hydrolysates. The optimal hydrolysis efficiency and iodine enrichment were obtained during 24-h incubation with papain in a 4.5-mM potassium iodide medium. The efficiency reached 98.22% with iodine concentrations of 2,664.91 and 9,200.67 μg/g iodine in pellet and supernatant, respectively.     

The gender- and fat depot-specific regulation of leptin, resistin and adiponectin genes expression by progesterone in rat

Progesterone affects lipid metabolism in adipose tissue and influences fat distribution in human. The aim of the study was to analyze the effect of progesterone on rat body and fat mass and on expression of genes encoding adipokines involved in the regulation of energy homeostasis. The results presented here indicate that progesterone administration to females caused increase in body and inguinal white adipose tissue mass. The increase of inguinal white adipose tissue mass is associated with the hypertrophy of adipocyte. The same dose of progesterone caused increase of its circulating concentration in males, however it barely reached the value observed in non-treated control females and did not have any effect on body and fat mass. The elevated circulating progesterone concentration was associated with an approximately 6- and 2-fold increase of leptin and resistin mRNA level respectively, and 2-fold decrease of adiponectin mRNA level only in inguinal white adipose tissue of females. RU 486, specific antagonist of progesterone receptor, abolished the effect of progesterone on the adipokine mRNA level in inguinal adipose tissue. In males, the elevated circulating progesterone concentration showed no effects on leptin, resistin or adiponectin mRNA level in inguinal, retroperitoneal or epididymal adipose tissue. Moreover, the results presented in this paper demonstrate a relatively high level of progesterone receptor mRNA in inguinal white adipose tissue of females, which was down-regulated in response to progesterone administration. In retroperitoneal adipose tissue of control females progesterone receptor mRNA level was approximately 3-fold lower as compared to inguinal adipose tissue. In inguinal, epididymal and retroperitoneal white adipose tissue of males progesterone receptor mRNA was hardly detected. Our results suggest that depot- and sex-dependent responsiveness of adipose tissue to the pharmacological dose of progesterone is controlled by both circulating concentration of progesterone and the white adipose tissue progesterone receptor level.     

Developing a denoising filter for electron microscopy and tomography data in the cloud

The low radiation conditions and the predominantly phase-object image formation of cryo-electron microscopy (cryo-EM) result in extremely high noise levels and low contrast in the recorded micrographs. The process of single particle or tomographic 3D reconstruction does not completely eliminate this noise and is even capable of introducing new sources of noise during alignment or when correcting for instrument parameters. The recently developed Digital Paths Supervised Variance (DPSV) denoising filter uses local variance information to control regional noise in a robust and adaptive manner. The performance of the DPSV filter was evaluated in this review qualitatively and quantitatively using simulated and experimental data from cryo-EM and tomography in two and three dimensions. We also assessed the benefit of filtering experimental reconstructions for visualization purposes and for enhancing the accuracy of feature detection. The DPSV filter eliminates high-frequency noise artifacts (density gaps), which would normally preclude the accurate segmentation of tomography reconstructions or the detection of alpha-helices in single-particle reconstructions. This collaborative software development project was carried out entirely by virtual interactions among the authors using publicly available development and file sharing tools.