Interactive effects of phosphate deficiency, sucrose and light/dark conditions on gene expression of UDP-glucose pyrophosphorylase in Arabidopsis

The effects of inorganic phosphate (Pi) status, light/dark and sucrose on expression of UDP-glucose pyrophosphorylase (UGPase) gene (Ugp), which is involved in sucrose/ polysaccharides metabolism, were investigated using Arabidopsis wild-type (wt) plants and mutants impaired in Pi and carbohydrate status. Generally, P-deficiency resulted in increased Ugp expression and enhanced UGPase activity and protein content, as found for wt plants grown on P-deficient and complete nutrient solution, as well as for pho1 (P-deficient) mutants. Ugp was highly expressed in darkened leaves of pho1, but not wt plants; daily light exposure enhanced Ugp expression both in wt and pho mutants. The pho1 and pho2 (Pi-accumulating) mutations had little or no effect on leaf contents of glucose and fructose, regardless of light/dark conditions, whereas pho1 plants had much higher levels of sucrose and starch in the dark than pho2 and wt plants. The Ugp was up-regulated when leaves were fed with sucrose in wt plants, but the expression in pho2 background was much less sensitive to sucrose supply than in wt and pho1 plants. Expression of Ugp in pgm1 and sex1 mutants (impaired in starch/sugar content) was not dependent on starch content, and not tightly correlated with soluble sugar status. Okadaic acid (OKA) effectively blocked the P-starvation and sucrose-dependent expression of Ugp in excised leaves, whereas staurosporine (STA) had only a small effect on both processes (especially in -P leaves), suggesting that P-starvation and sucrose effects on Ugp are transmitted by pathways that may share similar components with respect to their (in) sensitivity to OKA and STA. The results of this study suggest that Ugp expression is modulated by an interaction of signals derived from P-deficiency status, sucrose content and dark/light conditions, and that light/sucrose and P-deficiency may have additive effects on Ugp expression.     

Local and long-range structural effects caused by the removal of the N-terminal polypeptide fragment from immunoglobulin L chain lambda

The role of the N-terminal polypeptide fragment of the immunoglobulin l-chain in V domain packing stability, and the flexibility of the whole chain was approached by molecular dynamics simulation. The observations were supported by experimental analysis. The N-terminal polypeptide fragment appeared to be the low-stability packing element in the V domain. At moderately elevated temperature it may be replaced at its packing locus by Congo red and then removed by proteolysis. After removal of Congo red by adsorption to (diethylamino)ethyl (DEAE) cellulose, the stability of complete L chain and of L chain devoid of the N-terminal polypeptide fragment were compared. The results indicated that the N-terminal polypeptide fragment plays an essential role in the stability of the V domain. Its removal makes the domain accessible for ANS and Congo red dye binding without heating. The decreased domain stability was registered in particular as increased root mean square (RMS) fluctuation and higher susceptibility to proteolytic attack. The long-range effect was most clearly manifested at 340 K as independent V and C domain fluctuation in the l-chain devoid of the N-terminal polypeptide fragment. This is likely due to the lack of direct connections between the N- and C-termini of the V domain polypeptide. In a complete V domain the connection involves residues 8-12 and 106-110 in particular. Partial or complete disruption of this connection increases the freedom of V domain rotation, while its increased cohesion strengthens the coupling of the V and C domains, making the whole L chain less flexible.     

The TLR7/8 ligand resiquimod targets monocyte-derived dendritic cell differentiation via TLR8 and augments functional dendritic cell generation

Imidazoquinolone compounds, such as resiquimod are Toll-like receptor (TLR) 7/8 ligands representing novel immune response modifiers undergoing clinical testing. Resiquimod has been reported to modulate conventional human monocyte-derived DC (moDC) differentiation, but the role of TLR7 and TLR8 is unclear. We directly dissected the TLR7- and TLR8-dependency by employing selective TLR7 ligands and resiquimod-coculture experiments with inhibitory oligonucleotides (iODN) suppressing TLR7, TLR7+8 or TLR7+8+9. Selective TLR7 ligands did not affect conventional moDC differentiation as analyzed by CD14/CD1a expression. iODN experiments confirmed that resiquimod’s effects during DC differentiation were antagonized only with TLR8 iODNs. Direct comparison of resiquimod DC with TLR7- and control-DC revealed significantly higher T-cell costimulatory molecule and MHC class II expression. Resiquimod DC promoted significantly stronger allogeneic T-cell proliferation and stronger naïve CD4⁺ T-cell proliferation. These results indicate the relevance of TLR8 for human monocyte-derived DC differentiation and maturation and may be relevant for clinical trials employing resiquimod.     

Modulation of cell-cycle dynamics is required to regulate the number of cerebellar GABAergic interneurons and their rhythm of maturation

The progenitors of cerebellar GABAergic interneurons proliferate up to postnatal development in the prospective white matter, where they give rise to different neuronal subtypes, in defined quantities and according to precise spatiotemporal sequences. To investigate the mechanisms that regulate the specification of distinct interneuron phenotypes, we examined mice lacking the G1 phase-active cyclin D2. It has been reported that these mice show severe reduction of stellate cells, the last generated interneuron subtype. We found that loss of cyclin D2 actually impairs the whole process of interneuron genesis. In the mutant cerebella, progenitors of the prospective white matter show reduced proliferation rates and enhanced tendency to leave the cycle, whereas young postmitotic interneurons undergo severe delay of their maturation and migration. As a consequence, the progenitor pool is precociously exhausted and the number of interneurons is significantly reduced, although molecular layer interneurons are more affected than those of granular layer or deep nuclei. The characteristic inside-out sequence of interneuron placement in the cortical layers is also reversed, so that later born cells occupy deeper positions than earlier generated ones. Transplantation experiments show that the abnormalities of cyclin D2(-/-) interneurons are largely caused by cell-autonomous mechanisms. Therefore, cyclin D2 is not required for the specification of particular interneuron subtypes. Loss of this protein, however, disrupts regulatory mechanisms of cell cycle dynamics that are required to determine the numbers of interneurons of different types and impairs their rhythm of maturation and integration in the cerebellar circuitry.     

Human herpesvirus 1 UL24 gene encodes a potential PD-(D/E)XK endonuclease

Using Meta-BASIC, a highly sensitive method for detection of distant similarity between proteins, we have identified another potential PD-(D/E)XK endonuclease in human herpesvirus 1 (HHV-1) encoded by the UL24 gene. The universal presence of UL24 in completed herpesviral genomes of three major subfamilies, Alphaherpesvirinae, Betaherpesvirinae, and Gammaherpesvirinae, suggests a fundamental role for this predicted PD-(D/E)XK endonuclease activity in the viral life cycle.     

Immunoexpression of androgen receptors and aromatase in testes of patient with Klinefelter's syndrome

Klinefelter's syndrome (47, XXY) is the most common chromosome aneuploidy in men and is usually characterized by underdeveloped testes and sterility. The aim of the present study was to detect cellular distribution of androgen receptors (AR) and aromatase in testes of patient with KS. The tissue sections were processed for morphological and immunohistochemical staining. Additionally, levels of FSH, LH, PRL, estradiol, and testosterone were measured in the plasma. Morphological analysis revealed a complete absence of spermatogenesis. No germ cells were present in seminiferous tubules. In some tubules, nests of apparently degenerating Sertoli cells were found. In the interstitium, Leydig cell hyperplasia was observed. Using immunohistochemistry, nuclear AR staining was detected in Sertoli cells and peritubular cells, whereas in Leydig cells the staining was exclusively cytoplasmic. The immunostaining of aromatase was detected in the cytoplasm of Sertoli cells and Leydig cells. Increased levels of gonadotropins and decreased level of testosterone concomitantly with the cytoplasmic localization of AR in Leydig cells might contribute to the impaired testicular function in patient with KS.     

Bilateral convergence of pulmonary stretch receptor inputs on I beta-neurons in the cat

Extracellular recordings were made from inspiratory beta- (I beta) neurons in the nucleus of the tractus solitarius in decerebrate cats. A reversible direct current block of myelinated fibers in the ipsilateral vagus nerve was used to evaluate the input from pulmonary stretch receptor afferents (PSR) of the contralateral vagus to individual I beta-neurons. This block served to remove all ipsilateral (which includes all monosynaptic) inputs from PSR to I beta-cells. The effect of withholding inflation on the firing rate and the time of onset of firing of I beta-neurons was determined before, during and after application of the direct current block. There was considerable variation in the strengths of the inputs from the ipsilateral and contralateral nerves; some cells received PSR inputs from only the ipsilateral vagus, but the majority were excited with varying magnitude from both vagi. Several neurons had powerful excitatory inputs from PSR of the contralateral vagus, with the ipsilateral (monosynaptic) contribution being of minor importance.     

Computer Modeling of the Solution Conformation of Cyclic Enkephalins

Summary The probable conformations of two cyclic enkephalin analogs, DNS-cyclo[d-Dab-Gly-Trp-Leu] (I) and DNS-cyclo[d-Dab-Gly-Trp-d-Leu] (II) (DNS=dansyl), were determined by combining the results of NOE, vicinal coupling constant and fluorescence energy transfer measurements with theoretical calculations. The common feature of the conformations for both peptides is the presence of a β-turn at residues 2 and 3.     

Proteolytic Remodeling of the Synaptic Cell Adhesion Molecules (CAMs) by Metzincins in Synaptic Plasticity

Cell adhesion molecules participate in the formation, maturation, function and plasticity of synaptic connections. The growing body of evidence indicates that in the regulation of the synaptic plasticity, in which these molecules play pivotal role, also the proteolytic processes are involved. This review focuses on extracellular proteolysis of the cell adhesion molecules by specific subgroup of the matrix metalloproteinases, a disintegrin and metalloproteases and a disintegrin and metalloproteinase with thrombospondin motifs, jointly referred to as metzincins, in driving coordinated synaptic structural and functional modifications underlying synaptic plasticity in the adult brain.     

Active polyphenolic compounds,nutrient contents and antioxidant capacity of extruded fish feed containing purple coneflower (Echinacea purpurea (L.) Moench.)

The growth of fish is directly dependent on feed composition and quality. Medicinal plants can be added to fish feed as adjuvant therapy for the prevention of fish diseases. The purple coneflower (Echinacea purpurea (L.) Moench.) has been reported to have multiple biological effects, including immunomodulatory and antioxidant activity. The most active compounds of E. purpurea are polyphenols - caffeic acid derivatives: caftaric acid, chlorogenic acid, cynarin, echinacoside and cichoric acid.Due to a relatively limited number of studies on the use of the purple coneflower as a nutritional supplement for fish feeding, extruded fish feed with addition of Echinacea roots was produced. In the feed total phenolic content, selected polyphenol contents, the energetic value, nutrient contents and antioxidant capacity were examined.The results indicate that fish feed with addition of the Echinacea has a great potential to be a good source of natural radical scavengers, for example polyphenols, and nutritive ingredients. Antioxidant properties of feed were well correlated with the coneflower content. The study findings confirmed that high-temperature extrusion-cooking process does not deactivate phenolic antioxidant compounds, which are present both in the Echinacea roots and in the final product. Fish feed with addition of E. purpurea can be used as a nutritional supplement in the prevention of fish diseases caused by oxidative stress.