Interactions of quercetin and its lanthane complex with double stranded DNA/RNA and single stranded RNA: spectrophotometric sensing of poly G

Spectrophotometric titrations revealed that stability of the quercetin/double stranded (ds) DNA or double stranded (ds) RNA non-covalent complexes is significantly higher compared to the quercetin/ss-RNA complexes. This observation can easily be correlated with the significantly larger aromatic surface of base pairs compared to single nucleobases, and it is in good agreement with other experimental data pointing toward intercalative binding mode of quercetin. Fluorescence increase of quercetin induced by ds-RNA is significantly stronger than observed for ds-DNA, offering usage of quercetin as the ds-RNA selective fluorescent probe. Also, addition of poly G yielded more than order of magnitude stronger changes in UV/visible and fluorescence spectrum of quercetin compared to the changes upon addition of poly A and poly U revealing possible usage of quercetin as a powerful spectroscopic probe for poly G sequences. Stability and stoichiometry of lanthane(III)/quercetin complexes in physiologically relevant aqueous media was determined. The interactions of (LaQ)(3+) with double stranded DNA and RNA were significantly different compared to the free quercetin, revealing increase of complex stability and thus significant impact of La(III) in binding of (LaQ)(3+) to polynucleotides. Similar results were observed for interactions of (LaQ)(3+) with single stranded RNA.     

Developmental patterns of caspase-3, bax and bcl-2 proteins expression in the human spinal ganglia

The distribution of the bcl-2, bax and caspase-3 proteins was investigated in the cells of developing human spinal ganglia. Paraffin sections of 10 human conceptuses between 5th and 9th gestational weeks were analysed morphologically, immunohistochemically and by TUNEL-method. Cells positive to caspase-3 had brown stained nuclei or nuclear fragmentations. At earliest stages, 6% of ganglion population were caspase-3 positive cells. Later on, a significant increase in number of caspase-3 positive cells appeared, particularly in the ventral part of ganglia (12%), and subsequently decreased to 6%. TUNEL-positive cells had the same distribution pattern as caspase-3 positive cells. Bax-positive cells followed the developmental pattern similar to caspase-3 cells, changing in range between 20% and 32%. There were 8% of bcl-2 positive cells at earliest stages. They increased significantly in dorsal part of the ganglion during the 7th week (28%), and than dropped to 15% by the end of the 8th week. These findings suggest a ventro-dorsal course of development in human spinal ganglia. Number of bcl-2, bax and caspase-3 positive cells changed in a temporally and spatially restricted manner, coincidently with ganglion differentiation. While apoptosis might control cell number, bcl-2 could act in suppression of apoptosis and enhancement of cell differentiation.     

Multiple nutrients limit litterfall and decomposition in a tropical forest

To explore the importance of 12 elements in litter production and decomposition, we fertilized 36 1600 m²-plots with combinations of N, P, K, or micronutrients (i.e. B, Ca, Cu, Fe, Mg, Mn, Mo, S, Zn) for 6 years in a lowland Panamanian forest. The 90% of litter falling as leaves and twigs failed to increase with fertilization, but reproductive litter (fruits and flowers) increased by 43% with N. K enhanced cellulose decomposition; one or more micronutrients enhanced leaf-litter decomposition; P enhanced both. Our results suggest tropical forests are a non-Liebig world of multiple nutrient limitations, with at least four elements shaping rates of litterfall and decomposition. Multiple metallomic enzymes and cofactors likely create gradients in the break down of leaf litter. Selection favours individuals that make more propagules, and even in an N-rich forest, N is a non-substitutable resource for reproduction.     

Reproductive system and spermatozoa of <Emphasis Type="Italic">Paraturbanella teissieri</Emphasis> (Gastrotricha,Macrodasyida): implications for sperm transfer modality in Turbanellidae

The morphology of the reproductive apparatus of several species of Turbanellidae, which are sequential hermaphrodites, has been studied for a comparison with that of other Gastrotricha Macrodasyida, which are simultaneous hermaphrodites. The common structural plan of the genital system of Turbanellidae includes two testes which extend into two sperm ducts turning anteriorly and fusing in a midventral pore, two ovaries with oocytes maturing in a cephalic direction and only one accessory organ, a seminal receptacle, provided with an external pore. A possible sperm transfer modality alternative to that described in the literature is advanced. Spermatological characters of Paraturbanella teissieri have been compared with those of the two Turbanella species studied up to date. Turbanellidae share with other Macrodasyida the general model of spermatozoon, but are the only representatives of this taxon known so far which have sperm devoid of the striated cylinder around the axoneme. Both the structure of the reproductive apparatus and the fine morphology of the spermatozoa of Turbanellidae species agree with the evolutionary view, recently supported by morphological and molecular data, which puts this taxon on a separate clade, early divergent from the stem lineage of Macrodasyida.     

Saline Stress Alters the Temporal Patterns of Xylem Differentiation and Alternative Oxidase Expression in Developing Soybean Roots

We conducted a coordinated biochemical and morphometric analysis of the effect of saline conditions on the differentiation zone of developing soybean (Glycine max L.) roots. Between d 3 and d 14 for seedlings grown in control or NaCl-supplemented medium, we studied (a) the temporal evolution of the respiratory alternative oxidase (AOX) capacity in correlation with the expression and localization of AOX protein analyzed by tissue-print immunoblotting; (b) the temporal evolution and tissue localization of a peroxidase activity involved in lignification; and (c) the structural changes, visualized by light microscopy and quantified by image digitization. The results revealed that saline stress retards primary xylem differentiation. There is a corresponding delay in the temporal pattern of AOX expression, which is consistent with the xylem-specific localization of AOX protein and the idea that this enzyme is linked to xylem development. An NaCl-induced acceleration of the development of secondary xylem was also observed. However, the temporal pattern of a peroxidase activity localized in the primary and secondary xylem was unaltered by NaCl treatment. Thus, the NaCl-stressed root was specifically affected in the temporal patterns of AOX expression and xylem development.     

Uptake and Metabolism of Serotonin by Ependymal Primary Cultures

Serotonin uptake and metabolism was studied in ependymal primary cultures. Serotonin uptake was facilitated by two different systems, one of which was the neuronal serotonin transporter SERT, exhibiting a Vmax value of 3.8+/-0.1 pmol x min(-1) x (mg protein)(-1) and an apparent Michaelis-Menten constant of 0.41+/-0.03 microM. The main product of metabolism was 5-hydroxyindole acetic acid, which resulted from the action of monoamine oxidase A. This enzyme showed a maximal rate of 0.85+/-0.02 nmol x min(-1) x (mg protein)(-1) and a Michaelis-Menten constant of 78+/-5 microM. Ependymal cells were able to dispose of extracellular serotonin with initial rates of approximately 600 pmol x min(-1) x (mg protein)(-1) and of 4 pmol x min(-1) x (mg protein)(-1) when challenged with 500 microM and 1 microM extracellular serotonin, respectively. Ependymal cells are concluded to facilitate the "sink" action of the CSF by removing waste compounds upon passing of the fluid from the parenchymal extracellular space into the ventricular system.     

Partition behavior of CD133+ stem cells from human umbilical cord blood in aqueous two‐phase systems: In route to establish novel stem cell primary recovery strategies

Aqueous two‐phase systems (ATPS) represent a promising strategy for the recovery of CD133⁺ stem cells. This particular type of stem cells has great potential for research and clinical applications. Traditional [polyethylene glycol (PEG), dextran (DEX), and ficoll] and novel (Ucon) polymer–polymer ATPS were exploited to study the partitioning behavior of CD133⁺ stem cells and contaminants from human umbilical cord blood (HUCB). The aim of the study was to select conditions under which the product of interest and the contaminants concentrate in opposite phases. To accomplish this, three independent samples were tested: (1) enriched CD133⁺ sample, (2) whole HUCB (contaminants), and (3) complex sample (CD133⁺ stem cells and contaminants). The objective of this research was to evaluate the partition behavior of CD133⁺ in ATPS in route to establish the basis for the development of a novel and scalable purification bioprocess. In conclusion, the partitioning behavior of CD133⁺ stem cells and contaminants from complex samples was as follows: 59% of CD133⁺ stem cells fractionated to the top phase when employing ficoll 400,000–DEX 70,000 or 100% to the bottom phase with Ucon‐DEX 75,000 and PEG 8,000‐DEX 500,000 ATPS. In average, 35% of the contaminants partitioned to the top phase of the ficoll 400,000‐DEX 70,000 ATPS, 99% to the dextran rich phase of the Ucon‐DEX 75,000 systems and 97% to the bottom phase of the PEG 8,000‐DEX 500,000. Cell viability was at least 98% after ATPS recovery. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:700–707, 2014     

The regulation of cadherin-mediated adhesion by tyrosine phosphorylation/dephosphorylation of beta-catenin

The formation of stable cell-cell adhesions by type I cadherins depends on the association of their cytoplasmic domain with beta-catenin, and of beta-catenin with alpha-catenin. The binding of beta-catenin to these partners is regulated by phosphorylation of at least three critical tyrosine residues. Each of these residues is targeted by one or more specific kinases: Y142 by Fyn, Fer and cMet; Y489 by Abl; and Y654 by Src and the epidermal growth factor receptor. Developmental and physiological signals have been identified that initiate the specific phosphorylation and dephosphorylation of these residues, regulating cadherin function during neurite outgrowth, permeability of airway epithelium and synapse remodeling, and possibly initiating epithelial cell migration during development and metastasis.