cDNA structures and regulation of two interferon-induced human Mx proteins.

Human cells treated with interferon synthesize two proteins that exhibit high homology to murine Mx1 protein, which has previously been identified as the mediator of interferon-induced cellular resistance of mouse cells against influenza viruses. Using murine Mx1 cDNA as a hybridization probe, we have isolated cDNA clones originating from two distinct human Mx genes, designated MxA and MxB. In human fibroblasts, expression of MxA and MxB is strongly induced by alpha interferon (IFN-alpha), IFN-beta, Newcastle disease virus, and, to a much lesser extent, IFN-gamma, MxA and MxB proteins have molecular masses of 76 and 73 kilodaltons, respectively, and their sequences are 63% identical. A comparison of human and mouse Mx proteins revealed that human MxA and mouse Mx2 are the most closely related proteins, showing 77% sequence identity. Near their amino termini, human and mouse Mx proteins contain a block of 53 identical amino acids and additional regions of very high sequence similarity. These conserved sequences are also present in a double-stranded RNA-inducible fish gene, which suggests that they may constitute a functionally important domain of Mx proteins. In contrast to mouse Mx1 protein, which accumulates in the nuclei of IFN-treated mouse cells, the two human Mx proteins both accumulate in the cytoplasm of IFN-treated cells.     

Prediction of "hot spots" in interleukin-2 based on informational spectrum characteristics of growth-regulating factors. Comparison with experimental data

The Resonant Recognition Model (RRM) is a theoretical method for analysis of protein and nucleotide sequences, based on the Fourier transform of the numerical representation of sequences. The amplitude spectrum of this transform is designated Informational Spectrum (IS). There are certain common frequencies in IS of growth-regulating factors. These characteristic frequencies may correlate with their roles in cell proliferation and metabolism, and in antitumor activity. IS of IL-2 has prominent characteristics in the main frequency domain of growth factors, frequency domain of antitumor factors, and frequency domain characteristic for IL-2-alpha receptor. By means of the inverse method for these 3 domains, the amino acids in the sequence of human IL-2 that may be relevant to its biological function, the so-called "hot spots", were predicted. The most probable hot spots, obtained in this way, are in the potential binding site of IL-2 to its receptor, which agrees with experimental data.     

Resistance to influenza virus and vesicular stomatitis virus conferred by expression of human MxA protein.

MxA and MxB are interferon-induced proteins of human cells and are related to the murine protein Mx1, which confers selective resistance to influenza virus. In contrast to the nuclear murine protein Mx1, MxA and MxB are located in the cytoplasm, and their role in the interferon-induced antiviral state was unknown. In this report we show that transfected cell lines expressing MxA acquired a high degree of resistance to influenza A virus. Surprisingly, MxA also conferred resistance to vesicular stomatitis virus. Expression of MxA in transfected 3T3 cells had no effect on the multiplication of two picornaviruses, a togavirus, or herpes simplex virus type 1. Treatment of MxA-expressing cells with antibodies to mouse alpha-beta interferon did not abolish the resistance phenotype. The conclusion that resistance to influenza virus and vesicular stomatitis virus was due to the specific action of MxA is further supported by the observation that transfected 3T3 cell lines expressing the related MxB failed to acquire virus resistance.     

Strain improvement of Claviceps purpurea by protoplast fusion without introducing auxotrophic markers

Protoplasts of morphologically and biochemically different Claviceps purpurea strains producing ergotoxins were fused without introducing selective auxotrophic markers. Fused strains thus obtained differed significantly in biosynthetic activity and morphology from the prototrophic isolates obtained after fusion of the same parent strains marked by auxotrophy. Comparison of the two types of fused strains showed about tenfold higher alkaloid production in fusants obtained from prototrophic strains. Selected stable prototrophic isolates also showed a significant productivity improvement in comparison with the original parent strains. Correspondence to: M. Didek-Brumec     

Beyond the GTP-cap: Elucidating the molecular mechanisms of microtubule catastrophe

Almost 40 years since the discovery of microtubule dynamic instability, the molecular mechanisms underlying microtubule dynamics remain an area of intense research interest. The “standard model” of microtubule dynamics implicates a “cap” of GTP-bound tubulin dimers at the growing microtubule end as the main determinant of microtubule stability. Loss of the GTP-cap leads to microtubule “catastrophe,” a switch-like transition from microtubule growth to shrinkage. However, recent studies, using biochemical in vitro reconstitution, cryo-EM, and computational modeling approaches, challenge the simple GTP-cap model. Instead, a new perspective on the mechanisms of microtubule dynamics is emerging. In this view, highly dynamic transitions between different structural conformations of the growing microtubule end – which may or may not be directly linked to the nucleotide content at the microtubule end – ultimately drive microtubule catastrophe.     

Overexpression of the influenza virus polymerase can titrate out inhibition by the murine Mx1 protein.

The murine Mx1 protein is an interferon-inducible protein which confers selective resistance to influenza virus infection both in vitro and in vivo. The precise mechanism by which the murine Mx1 specifically inhibits replication of influenza virus is not known. Previously, sensitive replication systems for influenza virus ribonucleoprotein, in which a synthetic influenza virus-like ribonucleoprotein is replicated and transcribed by influenza virus proteins provided in trans, have been developed. With these systems, the antiviral activity of the murine Mx1 protein was examined. It was found that continued expression of influenza polymerase polypeptides via vaccinia virus vectors can titrate out the inhibitory action of the murine Mx1 protein. This titration of inhibitory activity also occurs when the viral PB2 protein alone is overexpressed, suggesting that an antiviral target for the murine Mx1 polypeptide is the viral PB2 protein.     

Lipid status association with 25-hydroxy vitamin D: Cross sectional study of end stage renal disease patients

BackgroundSome observational studies indicate an association of 25-hydroxy vitamin D (25(OH)D) insufficiency and atherogenic cholesterol concentrations. The aim of this study was to investigate relationship between 25(OH)D concentrations and lipid parameters in end stage renal disease (ESRD) patients, separately for predialysis, hemodialysis and peritoneal dialysis patients.MethodsWe have adjusted 25(OH)D concentrations for seasonal variability with cosinor analysis, and performed all further analysis using these corrected 25(OH)D concentrations. Concentrations of 25(OH)D and the lipid parameters were determined in 214 ESRD patients and 50 control group participants. The analysis included the measurement of 25(OH)D by HPLC, apolipoprotein (Apo) AI, ApoB and Lp(a) by nephelometry, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) by spectrophotometry and manually calculated ApoB/ApoAI and LDL-C/HDL-C ratio.ResultsESRD patients with adjusted 25(OH)D concentrations of 50 nmol/L had significantly higher TC (P = 0.005) and ApoAI (P = 0.049). Significantly higher HDLC (P = 0.011) and ApoAI (P = 0.020) were found in hemodialysis patients with the 25(OH)D concentrations of 50 nmol/L. The other analyzed lipid parameters differed significantly between predialysis, hemodialysis and peritoneal dialysis patients with 25(OH)D concentrations of < 50 nmol/L.ConclusionsOur study indicate the significant relationship between 25(OH)D repletion and optimal concentrations of lipid parameters in ESRD patients. Further research is necessary to explain whether joint evaluation of vitamin D status and lipid abnormalities could improve cardiovascular outcome in ESRD patients.     

Protected areas and prime hoverfly areas: Safe haven for hoverflies or not?

The efficiency of protected areas (PAs) has often been questioned due to global decline of biodiversity. Invertebrates, especially insects, have been historically underrepresented in conservation studies. Our study focuses on hoverflies, an important group of insect pollinators and proven to be good bioindicators. Research was focused in Serbia, one of Europe's hotspots of hoverfly diversity, with a long tradition of hoverfly research, which provided sufficient information for achieving our aims: identifying areas of high hoverfly diversity, evaluating the efficiency of PAs and prime hoverfly areas (PHAs) in the conservation of hoverflies, determining how well they cover the distribution of hoverfly species, especially those of conservation concern, and testing the importance of the size of the area for conservation of hoverfly diversity. We applied weighting of the species to help stress the importance of species of conservation concern. The results indicated that PHAs cover the areas with high hoverfly diversity better than PA networks, especially when it comes to species of conservation concern. Generalized linear model results showed that the area size was a significant predictor of number of species in both PA and PHA. This indicates that area size is key when designating new areas important for conservation, but there are also other factors that need to be taken into account, such as habitat quality or suitability. Studies like this are useful in aiding designation of new areas important for conservation of certain species and in identifying sampling gaps, which could potentially aim future research in that direction.