Dissolved Organic Nitrogen Hydrolysis Rates in Axenic Cultures of Aureococcus anophagefferens (Pelagophyceae): Comparison with Heterotrophic Bacteria

The marine autotroph Aureococcus anophagefferens (Pelagophyceae) was rendered axenic in order to investigate hydrolysis rates of peptides, chitobiose, acetamide, and urea as indicators of the ability to support growth on dissolved organic nitrogen. Specific rates of hydrolysis varied between 8 and 700% of rates observed in associated heterotrophic marine bacteria.     

PROGRESSION OF SPERMATIAL NUCLEAR DIVISION REQUIRES CALCIUM INFLUX DURING FERTILIZATION OF THE RED ALGA PALMARIA SP.1

During fertilization of the red alga Palmaria sp. (Palmariales), the prophase-arrested nucleus of the uninucleate spermatium resumes its division after direct attachment of the spermatium to the trichogyne of a carpogonium. Treatments that reduce Ca²⁺ influx inhibit the progression of spermatial nuclear division. The ratio of the number of spermatia released from prophase arrest (those in meta-phase to binucleate stages) to the total spermatia attached to trichogynes was significantly reduced by incubating the spermatia in the culture solution having low Ca²⁺ concentration. Similar inhibition was observed by addition of either inorganic (La³⁺ and Co²⁺) or organic (nifedipine and tetramethrin) Ca²⁺ channel inhibitors to the culture solution containing 10 mM Ca²⁺. These results indicate that the prophase/metaphase transition of spermatial nuclear division requires an influx of Ca²⁺ and suggest that Ca²⁺ acts as a second messenger to the mechanical or chemical stimulus that initiates mitotic progression of spermatia in this alga.     

Antioxidant status and lipid peroxidation in hemodialysis patients undergoing erythropoietin and erythropoietin-vitamin E combined therapy

In this study, plasma and red blood cell (RBC) antioxidant status and plasma lipid peroxidation were investigated in 46 hemodialysis patients. In addition, the effect of erythropoietin (EPO) and EPO-vitamin E combination therapy on plasma and RBC antioxidant status, and plasma lipid peroxidation were examined.

There were 10 healthy subjects in the control group and 10 hemodialysis patients in the untreated group. The third group included 36 hemodialysis patients that were given EPO (100 U/kg) for 3 months, 3 times per week. The fourth group included 36 hemodialysis-patients from the EPO group that were given EPO at a 50% decreased dose + vitamin E (300 mg/day) for 3 months.

MDA levels in the untreated group, the EPO group and the EPO + vitamin E groups were found to be higher than the control group (p<0.001, in both). Furthermore, MDA levels in both of the treatment groups were lower when compared to the untreated group (p<0.001, in both). Plasma vitamin E levels in the untreated, the EPO group and EPO + vitamin E groups were lower than the control group (p<0.001). In contrast, plasma vitamin E levels in the treatment groups were higher in comparison with the control group (p<0.05). SOD activities in the untreated, the EPO group and the EPO + vitamin E groups were found to be lower than the control group (p<0.001). SOD activities in the treatment groups were higher than the control group (p<0.001). The SOD activities in the EPO + vitamin E group increased when compared to the EPO group (p<0.001). CAT activities in the untreated, the EPO group and the EPO + vitamin E groups were found to be lower than the control group (p<0.001 in untreated and EPO groups, p<0.01 in EPO + vitamin E group). CAT activities in EPO and EPO + vitamin E groups were increased when compared to the untreated group (p<0.01).

In conclusion, our findings have shown that antioxidant status decreased and lipid peroxidation increased in hemodialysis patients. EPO has an antioxidant effect on the RBC and plasma antioxidant status, and plasma lipid peroxidation. These effects were moderately increased by the combination of vitamin E and EPO.     

Analysis of the internal motion of free and ligand-bound human lysozyme by use of 15N NMR relaxation measurement: a comparison with those of hen lysozyme

Human lysozyme has a structure similar to that of hen lysozyme and differs in amino acid sequence by 51 out of 129 residues with one insertion at the position between 47 and 48 in hen lysozyme. The backbone dynamics of free or (NAG)3-bound human lysozyme has been determined by measurements of 15N nuclear relaxation. The relaxation data were analyzed using the Lipari-Szabo formalism and were compared with those of hen lysozyme, which was already reported (Mine S et al.. 1999, J Mol Biol 286:1547-1565). In this paper, it was found that the backbone dynamics of free human and hen lysozymes showed very similar behavior except for some residues, indicating that the difference in amino acid sequence did not affect the behavior of entire backbone dynamics, but the folded pattern was the major determinant of the internal motion of lysozymes. On the other hand, it was also found that the number of residues in (NAG)3-bound human and hen lysozymes showed an increase or decrease in the order parameters at or near active sites on the binding of (NAG)3, indicating the increase in picosecond to nanosecond. These results suggested that the immobilization of residues upon binding (NAG)3 resulted in an entropy penalty and that this penalty was compensated by mobilizing other residues. However, compared with the internal motions between both ligand-bound human and hen lysozymes, differences in dynamic behavior between them were found at substrate binding sites, reflecting a subtle difference in the substrate-binding mode or efficiency of activity between them.     

Membranous glomerulonephritis development with Th2-type immune deviations in MRL/lpr mice deficient for IL-27 receptor (WSX-1)

MRL/lpr mice develop spontaneous glomerulonephritis that is essentially identical with diffuse proliferative glomerulonephritis (World Health Organization class IV) in human lupus nephritis. Lupus nephritis is one of the most serious complications of systemic lupus erythematosus. Diffuse proliferative glomerulonephritis is associated with autoimmune responses dominated by Th1 cells producing high levels of IFN-gamma. The initial mounting of Th1 responses depends on the function of the WSX-1 gene, which encodes a subunit of the IL-27R with homology to IL-12R. In mice deficient for the WSX-1 gene, proper Th1 differentiation was impaired and abnormal Th2 skewing was observed during infection with some intracellular pathogens. Disruption of the WSX-1 gene dramatically changed the pathophysiology of glomerulonephritis developing in MRL/lpr mice. WSX-1-/- MRL/lpr mice developed disease resembling human membranous glomerulonephritis (World Health Organization class V) with a predominance of IgG1 in glomerular deposits, accompanied by increased IgG1 and IgE in the sera. T cells in WSX-1-/- MRL/lpr mice displayed significantly reduced IFN-gamma production along with elevated IL-4 expression. Loss of WSX-1 thus favors Th2-type autoimmune responses, suggesting that the Th1/Th2 balance may be a pivotal determinant of human lupus nephritis development.     

Mobilization of human lymphoid progenitors after treatment with granulocyte colony-stimulating factor

Hemopoietic stem and progenitor cells ordinarily residing within bone marrow are released into the circulation following G-CSF administration. Such mobilization has a great clinical impact on hemopoietic stem cell transplantation. Underlying mechanisms are incompletely understood, but may involve G-CSF-induced modulation of chemokines, adhesion molecules, and proteolytic enzymes. We studied G-CSF-induced mobilization of CD34+ CD10+ CD19- Lin- and CD34+ CD10+ CD19+ Lin- cells (early B and pro-B cells, respectively). These mobilized lymphoid populations could differentiate only into B/NK cells or B cells equivalent to their marrow counterparts. Mobilized lymphoid progenitors expressed lymphoid- but not myeloid-related genes including the G-CSF receptor gene, and displayed the same pattern of Ig rearrangement status as their bone marrow counterparts. Decreased expression of VLA-4 and CXCR-4 on mobilized lymphoid progenitors as well as multipotent and myeloid progenitors indicated lineage-independent involvement of these molecules in G-CSF-induced mobilization. The results suggest that by acting through multiple trans-acting signals, G-CSF can mobilize not only myeloid-committed populations but a variety of resident marrow cell populations including lymphoid progenitors.     

Application of QSAR analysis to organic anion transporting polypeptide 1a5 (Oatp1a5) substrates

Organic anion transporting polypeptide 1a5, Slco1a5 (previously called Oatp3, Slc21a7) is a multispecific transmembrane transport protein that belongs to the OATP/SLCO superfamily of solute carriers. It is expressed in several epithelial barriers such as the small intestine and the choroid plexus where it might play an important role in the disposition of numerous endogenous and exogenous organic compounds. Since the molecular basis of the multispecificity of Oatp1a5 is not known and the three-dimensional structure not solved yet, we used three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques to obtain topological information on the substrate binding site of the protein. We aligned a heterogeneous data set of 18 Oatp1a5 substrates using the Genetic Algorithm Similarity Program (GASP) and performed comparative molecular field analysis (CoMFA) using this alignment. This resulted in a reasonable QSAR model including steric and electrostatic fields with a leave-one-out cross-validated r(cv)2 value of 0.705 and a no-cross-validated regression coefficient r2 value of 0.949. Based on the derived model we identified new potential Oatp1a5 substrates and confirmed their predicted apparent affinity values experimentally.     

Understanding genetic diversity of the liver fluke Fasciola hepatica

Economical breeding is important to obtain maximum gain from the breeding in the animal sector. The economic loss has to be eliminated or should be minimized. The liver fluke, Fasciola hepatica, present mostly in sheep and dairy cattle affect the yield of animals and even cause their death. To eliminate or minimize the impact of these parasites on the animals, it is important to understand the genetic diversity of the liver fluke populations and the relationship between parasite and host at regional bases. This research was carried out to determine diversity by sequence analysis of the mitochondrial ND1 gene and ribosomal ITS1 region.