Pyridoxal kinase (PLK; EC 2.7.1.35) is a key enzyme in the metabolism of vitamin B6 (VB6) in Bombyx mori. A fusion expressional vector pET-22b-BPLK-His was constructed using a sub-cloning technique, the recombinant B. mori PLK was then expressed in Escherichia coli, purified and characterized. Bioinformatics were used to deduce the protein structure and genomic organization of this enzyme. Using Ni Sepharose affinity column chromatography, the recombinant protein was purified to very high degree (approximately 90%). The recombinant PLK exhibits a high specific enzymatic activity (1800 nmol/min/mg of protein). The maximum catalytic activity of this enzyme was recorded over a narrow pH range (5.5-6.0) and Zn2+ is the most effective cation for catalysis under saturating substrate concentrations. When only triethanolamine is present as the cation, K+ is an activator of PLK. A double reciprocal plot of initial velocity suggests that the enzyme catalyses the reaction by means of a sequential catalytic mechanism. Under optimal conditions, the Km value for the substrates of ATP and pyridoxal are 57.9 ± 5.1 and 44.1 ± 3.9 µM. B. mori's genome contains a single copy of the PLK gene, which is 7.73 kb long and contains five exons and four introns, and is located on the eighth chromosome. The PLK may be a dimer with two identical subunits under native conditions, and it is hypothesized that each monomer contains eight α-helices (α1-8), nine β-strands (β1-9) and two segments of 310 helices. and Shuo-Hao HUANG, Wang MA, Ping-Ping ZHANG, Jian-Yun ZHANG, Yan-Feng XIE, Long-Quan HUANG.
The oldest butterfly fossil known, which was formed about 55 Ma in what is now Denmark, is described. The fragments of its forewing venation indicates it belongs to the Hesperiidae. Further reconstruction indicates that it fits in the Coeliadinae and is close to the extant genera Hasora and Burara. It is here described as Protocoeliades kristenseni gen. et sp. n. It is the first butterfly fossil found on a continent (Europe) where its closest relatives do not currently occur. Its position on the phylogenetic tree of the Coeliadinae and its importance in understanding the time dimension in the evolution of butterflies, and their ecological and biogeographic implications are discussed., Rienk De Jong., and Obsahuje bibliografii
In this review, we focused on the intersection between steroid metabolomics, obstetrics and steroid neurophysiology to give a comprehensive insight into the role of sex hormones and neuroactive steroids (NAS) in the mechanism controlling pregnancy sustaining. The data in the literature including our studies show that there is a complex mechanism providing synthesis of either pregnancy sust aining or parturition provoking steroids. This mechanism includes the boosting placental synthesis of CRH with approaching parturition inducing the excessive synthesis of 3β-hydroxy-5-ene steroid sulfates serving primarily as precursors for placental synthesis of progestogens, estrogens and NAS. The distribution and changing activities of placental oxidoreductases are responsible for the activation or inactivation of the aforementioned steroids, which is compartment-specific (maternal and fetal compartments) and dependent on gestational age, with a tendency to shift the production from the pregnancy-sustaining steroids to the parturition provoking ones with an increasing gestational age. The fetal and maternal livers catabolize part of the bioactive steroids and also convert some precursors to bioactive steroids. Besides the progesterone, a variety of its 5α/β-reduced metabolites may significantly influence the maintenance of human pregnancy, provide protection against excitotoxicity following acute hypoxic stress, and might also affect the pain perception in mother and fetus. and M. Hill ... [et al.].
The microalga Haematococcus pluvialis is a biotechnologically important microorganism producing a ketocarotenoid astaxanthin. Haematococcus exists either as metabolically active vegetative cells with a high chlorophyll content or astaxanthin-rich haematocysts (aplanospores). This microalga featuring outstanding tolerance to a wide range of adverse conditions is a highly suitable model for studies of freezing tolerance in phototrophs. The retention of H. pluvialis cell viability after freezing-thawing is ascribed to elevated antioxidant enzyme activity and high ketocarotenoid content. However, we report that only haematocysts characterized by a lower photosynthetic activity were resistant to freezing-thawing even without cryoprotectant addition. The key factors of haematocyst freezing tolerance were assumed to be a low water content, rigid cell walls, reduction of the membranous structures, photosynthesis downregulation, and low chlorophyll content. Collectively, viability of Haematoccus after freezing-thawing can be improved by forcing the transition of vegetative cells to freeze-tolerant haematocysts before freezing., K. Chekanov, S. Vasilieva, A. Solovchenko, E. Lobakova., and Obsahuje bibliografii
We characterized the photosynthetic growth of wild-type (WT) and QC-site mutant cells of the cyanobacterium Synechocystis sp. PCC 6803 grown in a photobioreactor under medium-intensity [~70 μmol(photon) m-2 s-1] and high-intensity [~200 μmol(photon) m-2 s-1] light conditions. Photosynthetic growth rate (the exponential phase) increased about 1.1-1.2 fold for the A16FJ, S28Aβ, and V32Fβ mutant compared with WT cells under medium-intensity light and about 1.2-1.3 fold under high-intensity light. Biomass production increased about 17-20% for A16FJ and S28Aβ mutant cells as compared with WT cells under medium-intensity light and about 14-17% for A16FJ and V32Fβ mutant cells under high-intensity light. The greater photosynthetic growth rate and biomass production of these QC-site mutant cells could be attributed to the increased photosynthesis efficiency and decreased dissipation of wasteful energy from phycobilisomes in mutants vs. WT cells. Our results support that manipulation of photoprotection may improve photosynthesis and biomass production of photosynthetic organisms., J.-Y. Huang, N.-T. Hung, K.-M. Lin, Y.-F. Chiu, H.-A. Chu., and Obsahuje bibliografické odkazy
Metabolic consequences of direct muscle trauma are insufficiently defined. Their effects on the ubiquitin-proteasome pathway (UPP) of protein degradation in human skeletal muscles are as yet unknown. Thus, we investigated whether the UPP is involved in the metabolic response evoked in directly traumatized human skeletal muscles. Biopsies were obtained from contused muscles after fractures and from normal muscles during elective implant removal (control). As estimated by western blot analyses, concentrations of free ubiquitin and ubiquitin protein conjugates were similar in extracts from injured and uninjured muscles. Ubiquitin protein ligation rates were reduced after injury (1.5±0.2 vs. 1.0±0.15 fkat/μg; p=0.04). Chymotryptic-, tryptic- and caspase-like proteasome peptidase activities (total activity minus activity in the presence of proteasome inhibitors) increased significantly after trauma (p=0.04 - 0.001). Significant increases in total chymotryptic- and caspase-like activities were attributable to proteasome activation. Our results extend the possible role of the UPP in muscle wasting to direct muscle trauma. They further suggest that the effects of direct mechanical trauma are not limited to the proteasome and imply that ubiquitin protein ligase systems are also involved. Based on the potential role of the UPP in systemic diseases, it might also be a therapeutic target to influence muscle loss in critically ill blunt trauma patients, in which large proportions of muscle are exposed to direct trauma. and Obsahuje bibliografii a bibliografické odkazy
Naše znalosti o ekologii a rozšíření řady druhů hub byly po dlouhou dobu založeny pouze na pozorování plodnic a sporulujících útvarů v terénu a na identifikaci izolovaných druhů hub. Nedávné pokroky a dostupnost metod založených na studiu DNA a jejich téměř rutinní používání v laboratořích rozšířilo naše znalosti o substrátech kolonizovaných různými druhy hub. Na druhou stranu se ukázalo, že některé druhy kolonizují stejný substrát, ale na geograficky velmi vzdálených lokalitách. Některé druhy ani nelze zařadit do jasně vymezené ekologické skupiny, mění svou ekologii v průběhu svého životního cyklu., Our information about the ecology and distribution of particular fungal species has for a long time been based only on observations of fruit bodies and sporulating structures in the field and on identification of isolated fungal strains. Recent developments in molecular methods and their routine use in mycology have revealed that some fungi may colonize different substrates than originally supposed. On the other hand, other fungi colonize their typical habitats in localities that are enormously distant from each other. Some fungi may not be easily assigned to a single ecological group, as they change various life styles during their life cycle., and Ondřej Koukol.
1_Macrosiphum euphorbiae. Three tomato cultivars (Scintilla, Beefmaster and Rio Grande) were used in the experiments. The results for three watering regimes were compared with those of a control, which was well watered every three days: stressed plants received one third of the water supplied to the control over each three-day interval (experiment 1); stressed plants received a gradually decreasing amount of water (100% at the first watering and then 80%, 60%, 50%, 40% and 20%) every three days (experiment 2); stressed plants received the same amount of water as the control but at longer intervals, that is when evident signs of wilting appeared (experiment 3). The results showed that water stress either enhanced, had an adverse effect or had no effect on aphid population growth, depending on the cultivar and watering regime. No difference was recorded in the population dynamics of M. euphorbiae feeding on Beefmaster tomato plants subjected to different levels of water stress. In the case of the cultivar Scintilla, live aphids were less abundant on stressed plants than on well watered ones in experiment 1 and 3 but not in experiment 2., 2_The highest variability in aphid population dynamics on the plants grown under the different water stress protocols was recorded on the cultivar Rio Grande. In experiment 1, the initial peak in aphid numbers was higher on the water stressed plants than on the control and then decreased to lower numbers than on the control. In experiment 2, there were no differences in the numbers of aphids infesting stressed and control plants. In experiment 3, there were fewer aphids on stressed than on control plants after six days, as in experiment 1, but there was no initial peak in aphid numbers., Anna R. Rivelli ... [et al.]., and Obsahuje seznam literatury
Oxidative stress has been implicated to play a major role in aging and age-related diseases. In the present study, we investigated the effects of aging on the total antioxidant capacity, uric acid, lipid peroxidation, total sulfhydryl group content and damage to DNA in adult (6 months), old (15 months) and senescent (26 months) male Wistar rats. The antioxidant capacity, determined by phycoerythrin-based TRAP method (total peroxyl radical-trapping potential) was significantly decreased in the plasma and myocardium of old and senescent rats, whereas plasma level of uric acid was elevated in 26-month-old rats. Age-related decline in plasma and heart antioxidant capacity was accompanied by a significant loss in total sulfhydryl group content, increased lipid peroxidation and higher DNA damage in lymphocytes. Correlations between TRAP and oxidative damage to lipids, proteins and DNA suggest that the decline in antioxidant status may play an important role in age-related accumulation of cell damage caused by reactive oxygen species., M. Sivoňová, Z. Tatarková, Z. Ďuračková, D. Dobrota, J. Lehotský, T. Matáková, P. Kaplán., and Obsahuje bibliografii a bibliografické odkazy