Photochemical and photophosphorylation activities of chloroplasts and leaf mesostructure in Chinese cabbage plants grown under illumination with light-emitting diodes

Leaf mesostructure, photochemical activity, and chloroplast photophosphorylation (PP) in the fourth true leaf of 28-day-old Chinese cabbage (Brassica chinensis L.) plants were investigated. Plants were grown under a light source based on red (650 nm) and blue (470 nm) light-emitting diodes (LED) with red/blue photon flux ratio of 7: 1 and under illumination with high-pressure sodium lamp (HPSL) at photon flux densities of 391 ± 24 μmol/(m² s) (“normal irradiance”) and 107 ± 9 μmol/(m² s) (“low irradiance”) in photosynthetically active range. At normal irradiance, the leaf area in plants grown under HPSL was twofold higher than in LED-illuminated plants; other parameters of leaf mesostructure were little affected by spectral quality of incident light. The lowering of growth irradiance reduced the majority of leaf mesostructure parameters in plants grown under illumination with HPSL, whereas in LED-illuminated plants the lowered irradiance reduced only specific leaf weight but increased the leaf thickness and dimensions of mesophyll cells and chloroplasts. The photochemical activity of isolated chloroplasts was almost independent of growth irradiance and light spectral quality. Light quality and intensity used for plant growing had a considerable impact on PP in chloroplasts. At normal light intensity, the highest activity of noncyclic PP in chloroplasts was observed for plants grown under HPSL; at low light intensity the highest rates of PP were noted for plants grown under LED. The P/2e⁻ ratio, which characterizes the degree of PP coupling to electron transport in the chloroplast electron transport chain, showed a similar pattern. Thus, the narrow-band spectrum of the light source had little influence on leaf mesostructure and electron transport rates. However, this spectrum significantly affected the chloroplast PP activity. The PP patterns at low and normal light intensities were opposite for plants grown under LED and HPSL light sources. We suppose that growing plants under LED array at normal light intensity disturbed the chloroplast coupling system, thus preventing the effective use of light energy for ATP synthesis. At low light intensity, chloroplast PP activity was significantly higher under LED illumination, but plant growth was suppressed because of impaired adaptation to low light intensity.     

Propagation of shear waves in muscle tissue

A mathematical model of the propagation of acoustic shear waves in muscle tissue is considered. Muscle is modeled as an incompressible transversely isotropic viscoelastic continuum with quasi-one-dimensional active tension. There are two types of shear waves in an infinite medium. Waves of the second type (transverse) propagate without decay even when myofibril viscosity is taken into account. A problem of standing transverse waves in a rectangular layer was investigated numerically. The values of the problem parameters are found for which one can easily estimate the active tension (or muscle tone) from the characteristics of standing waves. This value is informative for diagnostics of the muscle state.     

Separation of dissociated thyroid follicular and parfollicular cells: association of serotonin binding protein with parafollicular cells

Parafollicular cells (PC) of the sheep thyroid gland are neural crest derivatives that synthesize and release the biogenic amine serotonin (5-HT) as well as the hormone calcitonin. The thyroid also contains a highly specific serotonin-binding protein (SBP). Separation of dissociated thyroid cells was done to study the cellular localization of SBP and to develop a means of isolating PC for study. Various methods were used to obtain an enriched and purified population of PC. Minced thyroid glands were enzymatically dissociated and the cells were layered on a Ficoll linear density gradient. Fractions obtained from the gradient were examined for cell number, viability, 5-HT concentration, SBP activity, and morphology by electron microscopy. One of the fractions was found to be enriched in PC. High levels of 5-HT and SBP were also found in this fraction, whereas these levels were low where the majority of cells were found. This PC-rich fraction, however, contained numerous follicular cells (FC); therefore, additional approaches to cell separation were used. FC can be stimulated in vitro with thyroid stimulating hormone (TSH) to become intensely phagocytic. When stimulated cells were incubated in the presence of silica microspheres, the FC engulfed the microspheres, which were toxic to them. PC did not become phagocytic and were unharmed by the microspheres. Suspended cells, after incubation with microspheres, were centrifuged on a discontinuous gradient, and a PC-rich fraction was obtained. Silica, however, interfered with analysis of SBP. Another method to take advantage of the phagocytic potential of FC was therefore used. TSH-stimulated cell suspensions were passed through a column of sepharose to which thyroglobulin had been coupled. Stimulated FC apparently adhered to the beads and were retained by the columns. Fractions eluting from the columns were greatly enriched with PC. These fractions contained high levels of 5-HT and SBP, and considerably reduced FC contamination was found by quantitative electron microscopy. It is concluded that SBP is localized to PC in the sheep thyroid. The idea that these cells resemble serotonergic neurons in their mechanisms of 5-HT storage is supported.     

Sulfocoumarins as dual inhibitors of human carbonic anhydrase isoforms IX/XII and of human thioredoxin reductase

Abstract

The hypothesis that sulfocoumarin acting as inhibitors of human carbonic anhydrase (CA, EC 4.2.1.1) cancer-associated isoforms hCA IX and – hCA XII is being able to also inhibit thioredoxin reductase was verified and confirmed. The dual targeting of two cancer cell defence mechanisms, i.e. hypoxia and oxidative stress, may both contribute to the observed antiproliferative profile of these compounds against many cancer cell lines. This unprecedented dual anticancer mechanism may lead to a new approach for designing innovative therapeutic agents.     

Somatic embryogenesis from ovaries,developing ovules and immature zygotic embryos,and improved embryo development of <Emphasis Type="Italic">Castanea sativa</Emphasis>

Somatic embryogenesis of European chestnut (Castanea sativa Mill.) was obtained using juvenile tissue cultured on P24 medium with 5 M 2,4-dichlorophenoxyacetic acid plus 0.5 M 6-benzylaminopurine (BA) for three weeks and then cultured on 0.89 M BA. Induction frequency with ovaries ranged from 2.0 to 19.1 % and was observed in tissue collected 2 to 8 weeks postanthesis, ovules used as a starting tissue gained 0.8 to 7.8 %, 3 to 9 weeks postanthesis. Zygotic embryos collected 5 to 10 weeks postanthesis formed 10.5 to 57.1 % somatic embryos, respectively. The culture lines were maintained via secondary embryogenesis on P24 medium with 0.89 M BA. Development and maturation were stimulated on P24 medium with increased agar concentration (1.1 %). Five plantlets were transferred to substrate and acclimatized successfully in greenhouse.     

Granule-bound starch synthase: structure, function, and phylogenetic utility

Interest in the use of low-copy nuclear genes for phylogenetic analyses of plants has grown rapidly, because highly repetitive genes such as those commonly used are limited in number. Furthermore, because low- copy genes are subject to different evolutionary processes than are plastid genes or highly repetitive nuclear markers, they provide a valuable source of independent phylogenetic evidence. The gene for granule-bound starch synthase (GBSSI or waxy) exists in a single copy in nearly all plants examined so far. Our study of GBSSI had three parts: (1) Amino acid sequences were compared across a broad taxonomic range, including grasses, four dicotyledons, and the microbial homologs of GBSSI. Inferred structural information was used to aid in the alignment of these very divergent sequences. The informed alignments highlight amino acids that are conserved across all sequences, and demonstrate that structural motifs can be highly conserved in spite of marked divergence in amino acid sequence. (2) Maximum-likelihood (ML) analyses were used to examine exon sequence evolution throughout grasses. Differences in probabilities among substitution types and marked among-site rate variation contributed to the observed pattern of variation. Of the parameters examined in our set of likelihood models, the inclusion of among-site rate variation following a gamma distribution caused the greatest improvement in likelihood score. (3) We performed cladistic parsimony analyses of GBSSI sequences throughout grasses, within tribes, and within genera to examine the phylogenetic utility of the gene. Introns provide useful information among very closely related species, but quickly become difficult to align among more divergent taxa. Exons are variable enough to provide extensive resolution within the family, but with low bootstrap support. The combined results of amino acid sequence comparisons, maximum-likelihood analyses, and phylogenetic studies underscore factors that might affect phylogenetic reconstruction. In this case, accommodation of the variable rate of evolution among sites might be the first step in maximizing the phylogenetic utility of GBSSI.      

Dietary regulation of mammary lipogenesis in lactating rats.

The proportion of medium-chain fatty acids (C8:0, C10:0 and C12:0) in rat milk increased significantly between day 4 and day 8 of lactation and for the remainder of lactation these acids comprised 40-50mol% of the total fatty acids. The milk fatty acid composition from day 8 was markedly dependent on the presence of dietary fat and altered to include the major fatty acids of the fats (peanut oil, coconut oil and linseed oil). The distribution of fatty acids made within the gland, however, was independent of dietary lipid and C8:0, C10:0 and C12:0 acids accounted for over 70% of the fatty acids made. The rates of lipogenesis in both the mammary gland and liver determined in vivo after the administration of 3H2O were affected by the presence of dietary lipid. In the mammary gland the rate for rats fed a diet containing peanut oil for 7 days was only one fifth that for rats fed a fat-free diet. Coconut oil also suppressed lipogenesis. Both dietary fats also suppressed lipogenesis in the liver.     

Association of genes of different functional classes with type 1 diabetes

The genetic structure of susceptibility to type 1 diabetes (T1D) in the population of Tomsk was studied. We had a group of T1D patients (N = 285) and a population sample (N = 300) and we studied 58 SNPs localized in the 47 genes which products are involved in various metabolic pathways and processes as fibrogenesis, endothelial dysfunction, and inflammation. Genotyping was performed by mass spectrometry using the Sequenom MassARRAY system (United States). We compared the group of T1D patients and the population sample and found an association with the predisposition to disease for seven markers: rs3765124 of the ADAMDEC1 gene, genotype AA (p = 0.004), allele A (p = 0.033); rs1007856 of the ITGB5 gene, genotype TT (p = 0.015), allele T (p = 0.036); rs20579 of the LIG1 gene, genotype CC (p = 0.004), allele C (p = 0.002); rs12980602 of the IFNL2 gene, allele C (p = 0.029); rs4986819 of the PARP4 gene, allele C (p = 0.044); rs1143674 of the ITGA4 gene genotype GG (p = 0.002); rs679620 of the MMP3 gene, genotype AA (p = 0.008). Thus, the products of genes associated with T1D belong to different molecular classes: metalloproteases (ADAMDEC1, MMP3), cytokines (IL28A), cell surface receptors (ITGA4), adhesion molecules (ITGB5), DNA ligases (LIG1), and ribosyltransferase enzymes (PARP4). The ADAMDEC1, ITGA4, and ITGB5 genes belong to two biological processes: cell communication and signal transduction. The LIG1 and PARP4 genes regulate the metabolism of nucleic acids, MMP3 is involved in the regulation of protein metabolism, and the IFNL2 is involved in the immune response.