Coronaviruses in Avian Species - Review with Focus on Epidemiology and Diagnosis in Wild Birds.

Coronaviruses (CoVs) are a large group of enveloped viruses with a single-strand RNA genome, which continuously circulate in mammals and birds and pose a threat to livestock, companion animals, and humans. CoVs harboured by avian species are classified to the genera gamma- and deltacoronaviruses. Within the gamma-CoVs the main representative is avian coronavirus, a taxonomic name which includes the highly contagious infectious bronchitis viruses (IBVs) in chickens and similar viruses infecting other domestic birds such as turkeys, guinea fowls, or quails. Additionally, IBVs have been detected in healthy wild birds, demonstrating that they may act as the vector between domestic and free-living birds. Moreover, CoVs other than IBVs, are identified in wild birds, which suggests that wild birds play a key role in the epidemiology of other gammaCoVs and deltaCoVs. Development of molecular techniques has significantly improved knowledge of the prevalence of CoVs in avian species. The methods adopted in monitoring studies of CoVs in different avian species are mainly based on detection of conservative regions within the viral replicase, nucleocapsid genes, and 3'UTR or 5'UTR. The purpose of this review is to summarise recent discoveries in the areas of epidemiology and diagnosis of CoVs in avian species and to understand the role of wild birds in the virus distribution.

Ultrasensitive hexavalent chromium determination at bismuth film electrode prepared with mediator.

A bismuth film electrode prepared in situ with a reversibly deposited mediator (Zn) applied for ultrasensitive determination of Cr(VI) using differential pulse catalytic adsorptive stripping voltammetry is presented. The optimization of experimental conditions such as composition of the supporting electrolyte, potential and time of bismuth film formation as well as analyte accumulation, and DP mode parameters is reported. For 180 s accumulation time, very low limits of detection and quantification of Cr(VI) were obtained, with 5.8 × 10-14 and 1.9 × 10-13 mol L-1, respectively. The relative standard deviation for 5.0 × 10-13 mol L-1 of Cr(VI) was 3.9% (n = 5). Finally, the proposed procedure was applied to determine Cr(VI) in the certified reference materials - NASS-6 (seawater), SLEW-3 (estuarine water) and TMRAIN-04 (rainwater) - as well as in river water samples. Furthermore, the obtained results show that the proposed voltammetric procedure employing the bismuth film electrode prepared with mediator appears to form a very promising tool for the speciation of chromium at ultratrace level.

Development simple and sensitive voltammetric procedure for ultra-trace determination of U(VI).

A simple and sensitive adsorptive stripping voltammetric procedure for the determination of trace concentration of U(VI) in natural water samples was developed. In order to remove surface active compounds from water sample solutions, a TiO2/Al2O3 photocatalysis system was applied. The linear calibration graph of U(VI) in the simultaneous presence of 2mgL-1 anionic, cationic and nonionic surfactants, in the range from 5×10-10 to 2×10-8molL-1 (180s) was achieved. The detection limit obtained in the solution after the use of UV-irradiation (10min) with TiO2/Al2O3 photocatalyst (0.9g) is equal to 2.3×10-10mol L-1. The presented procedure was successfully applied to uranium determination in SLEW-3 certified reference material, and to river water samples. In addition, a very low detection limit (2.9×10-11molL-1) for accumulation time of 180s was achieved due to application of a reversible deposited mediator (Zn) in the step of lead film electrode preparation.

Structure of an early native-like intermediate of ß2-microglobulin amyloidogenesis.

To investigate early intermediates of ß2-microglobulin (ß2m) amyloidogenesis, we solved the structure of ß2m containing the amyloidogenic Pro32Gly mutation by X-ray crystallography. One nanobody (Nb24) that efficiently blocks fibril elongation was used as a chaperone to co-crystallize the Pro32Gly ß2m monomer under physiological conditions. The complex of P32G ß2m with Nb24 reveals a trans peptide bond at position 32 of this amyloidogenic variant, whereas Pro32 adopts the cis conformation in the wild-type monomer, indicating that the cis to trans isomerization at Pro32 plays a critical role in the early onset of ß2m amyloid formation.

Atomic structure of a nanobody-trapped domain-swapped dimer of an amyloidogenic beta2-microglobulin variant.

Atomic-level structural investigation of the key conformational intermediates of amyloidogenesis remains a challenge. Here we demonstrate the utility of nanobodies to trap and characterize intermediates of ß2-microglobulin (ß2m) amyloidogenesis by X-ray crystallography. For this purpose, we selected five single domain antibodies that block the fibrillogenesis of a proteolytic amyloidogenic fragment of ß2m (ΔN6ß2m). The crystal structure of ΔN6ß2m in complex with one of these nanobodies (Nb24) identifies domain swapping as a plausible mechanism of self-association of this amyloidogenic protein. In the swapped dimer, two extended hinge loops--corresponding to the heptapetide NHVTLSQ that forms amyloid in isolation--are unmasked and fold into a new two-stranded antiparallel ß-sheet. The ß-strands of this sheet are prone to self-associate and stack perpendicular to the direction of the strands to build large intermolecular ß-sheets that run parallel to the axis of growing oligomers, providing an elongation mechanism by self-templated growth.

Partial trisomy 11, dup(11)(q23q13), as a defect characterizing lymphomas with Burkitt pathomorphology without MYC gene rearrangement.

Burkitt lymphoma (BL) is an aggressive non-Hodgkin lymphoma characterized by specific morphological and immunophenotypic features. The basic genetic feature of BL is the rearrangement of MYC gene, visible as t(8;14)(q24;q32) translocation or its variant. However, some lymphomas with characteristic BL morphology are nowadays diagnosed as B-cell lymphoma unclassifiable with features intermediate between DLBCL and BL (Inter-DLBCL/BL) for biological or clinical reasons. We present four lymphomas without the MYC rearrangement presented typical Burkitt morphology, FCM immunophenotype with some deviations when compared to a typical BL. The cases were finally diagnosed as Inter-DLBCL/BL. All of them presented a recurrent abnormality within the chromosome 11: dup(11)(q23q13). We suppose that the dup(11)(q23q13), in absence of the MYC gene rearrangement, is connected with borderline lymphomas with a morphology similar or identical to that of the Burkitt lymphoma. Identifying such an aberration may be helpful in the diagnostics of Inter-DLBCL/BL eventually forming a distinct subgroup of lymphomas.

Yeast holoenzyme of protein kinase CK2 requires both beta and beta' regulatory subunits for its activity.

Protein kinase CK2 is a highly conserved Ser/Thr protein kinase that is ubiquitous among eucaryotic organisms and appears to play an important role in many cellular functions. This enzyme in yeast has a tetrameric structure composed of two catalytic (alpha and/or alpha') subunits and two regulatory beta and beta' subunits. Previously, we have reported isolation from yeast cells four active forms of CK2, composed of alphaalpha'betabeta', alpha2betabeta', alpha'2betabeta' and a free alpha'-catalytic subunit. Now, we report that in Saccharomyces cerevisiae CK2 holoenzyme regulatory beta subunit cannot substitute other beta' subunit and only both of them can form fully active enzymatic unit. We have examined the subunit composition of tetrameric complexes of yeast CK2 by transformation of yeast strains containing single deletion of the beta or beta' regulatory subunits with vectors carrying lacking CKB1 or CKB2 genes. CK2 holoenzyme activity was restored only in cases when both of them were present in the cell. Additional, co-immunoprecypitation experiments show that polyadenylation factor Fip1 interacts with catalytic alpha subunits of CK2 and interaction with beta subunits in the holoenzyme decreases CK2 activity towards this protein substrate. These data may help to elucidate the role of yeast protein kinase CK2beta/beta' subunits in the regulation of holoenzyme assembly and phosphotransferase activity.

Different properties of four molecular forms of protein kinase CK2 from Saccharomyces cerevisiae.

CK2 is a pleiotropic constitutively active serine/threonine protein kinase composed of two catalytic alpha- and two regulatory beta-subunits, whose regulation is still not well understood. It seems to play an essential role in regulation of many cellular processes. Four active forms of CK2, composed of alphaalpha'betabeta', alpha(2)betabeta', alpha'(2)betabeta', and a free alpha'-subunit were isolated from wild-type yeast and strains containing a single deletion of the catalytic subunit. Each species exhibits properties typical for CK2, but they differ in substrate specificity and sensitivity to inhibitors. This suggests that each CK2 isomer may regulate different process or may differ in the way of its regulation.

TBBz but not TBBt discriminates between two molecular forms of CK2 in vivo and its implications.

Two ATP-competitive inhibitors-4,5,6,7-tetrabromo-benzotriazole (TBBt) and 4,5,6,7-tetrabromo-benzimidazole (TBBz) have been shown to decrease activity of CK2 holoenzyme. Surprisingly it occurs that TBBz contrary to TBBt does not inhibit free catalytic subunit CK2 [Formula: see text]. Both inhibitors are virtually inactive against RAP protein kinase. The above-mentioned protein kinases phosphorylate in vitro a set of acidic ribosomal P-proteins of the 60S ribosomal subunit. Such a modification is one of the mechanisms regulating translational activity of ribosomes in vivo. Application of these two very selective inhibitors allows us to define the role of free catalytic [Formula: see text] subunit of CK2 in phosphorylation of ribosomal proteins. It occurs that CK2 [Formula: see text] but not CK2 holoenzyme is responsible for phosphorylation of P-proteins in vivo. Moreover, elimination of both forms of protein kinase CK2 (hCK2 and CK2 [Formula: see text] ) activity in living cells led to dramatic loss of the translational activity of the ribosome.