Prevalence of agglutinating antibodies against<Emphasis Type="Italic"> Listeria monocytogenes</Emphasis> in chicks of the white stork (<Emphasis Type="Italic">Ciconia ciconia</Emphasis> Linnaeus, 1758) in Poland

In 2002 and 2003, blood samples from white stork (Ciconia ciconia) chicks were examined for the presence of antibodies against Listeria monocytogenes. Listeria antibodies were detected in 121 (59%) of 205 chick samples. The probability of Listeria antibodies being present increased with chick age; chicks detected with Listeria antibodies were in better condition than those without the bacterium.     

Immunohistochemical localization of androgen receptor and aromatase in the ovary of the pregnant pig

The distribution of androgen receptor (AR) and cytochrome P450 aromatase was investigated in paraffin sections of pregnant pig ovary. Ovarian follicles and corpora lutea were isolated from ovaries obtained on Days 10, 18, 32, 71 and 90 post coitum (p.c.). Androgen receptor was localized in the nuclei of granulosa cells of follicles of various sizes. In addition, some follicles demonstrated staining in the nuclei of theca interna cells. Stroma cells also exhibited a positive immunostaining. At early and mid pregnancy (up to Day 71) AR was expressed in the nuclei of luteal cells. Corpora lutea of Day 71 showed mainly cytoplasmic staining while on Day 90 almost all luteal cells showed staining exclusively in the cytoplasm. Immuno-staining for the presence of cytochrome P450 aromatase was very faint in all investigated ovarian structures. The results could suggest that the process of androgen aromatization plays a negligible role in the ovary of the pregnant pig.     

Characterisation of a highly specific, endogenous inhibitor of cysteine protease from Staphylococcus epidermidis, a new member of the staphostatin family

Staphostatins, a novel family of cysteine protease inhibitors with a unique mechanism of action and distinct protein fold has recently been discovered. In this report we describe the properties of Staphylococcus epidermidis staphostatin A (EcpB), a new member of the family. As for other staphostatins, the recombinant S. epidermidis staphostatin A exerted very narrow inhibitory specificity, limited to cysteine protease from the same species. The closely related proteases from S. aureus cleaved the inhibitor at the reactive site peptide bond and inactivated it. The EcpB homologue, S. aureus staphostatin A (ScpB), was also susceptible to proteolytic cleavage at the same site by non-target cysteine proteases. Conversely, S. aureus staphostatin B (SspC) was resistant to such proteolysis. The difference in the susceptibility of individual inhibitors to proteolytic cleavage at the reactive site suggests subtle variations in the mechanism of interaction with cysteine proteases.     

Crystal structure of MboIIA methyltransferase

DNA methyltransferases (MTases) are sequence-specific enzymes which transfer a methyl group from S-adenosyl-L-methionine (AdoMet) to the amino group of either cytosine or adenine within a recognized DNA sequence. Methylation of a base in a specific DNA sequence protects DNA from nucleolytic cleavage by restriction enzymes recognizing the same DNA sequence. We have determined at 1.74 A resolution the crystal structure of a beta-class DNA MTase MboIIA (M.MboIIA) from the bacterium Moraxella bovis, the smallest DNA MTase determined to date. M.MboIIA methylates the 3' adenine of the pentanucleotide sequence 5'-GAAGA-3'. The protein crystallizes with two molecules in the asymmetric unit which we propose to resemble the dimer when M.MboIIA is not bound to DNA. The overall structure of the enzyme closely resembles that of M.RsrI. However, the cofactor-binding pocket in M.MboIIA forms a closed structure which is in contrast to the open-form structures of other known MTases.     

Siderophores and hemolysins in iron aquisition by Acinetobacter genus

In 60 strains of Acinetobacter genus isolated from clinical material belonging to species A. baumannii, A. haemolyticus, A. junii and A. lwoffii a hydroxamate and phenol-catechol class siderophores was identified by chemical and biological testes. A correlation between siderophores production and growth intensity, species affiliation and origin of strains was found.     

Fluorescent in situ sequencing on polymerase colonies

Integration of DNA isolation, amplification, and sequencing can be achieved by the use of polymerase colonies (polonies) and cycles of fluorescent dNTP incorporation. In this paper, we present four advances that bring us closer to sequencing genomes cost-effectively using the polony technology. First, a polymerase trapping technique enables efficient nucleotide extension by DNA polymerase in a polyacrylamide matrix and eliminates loss of enzyme during sequencing cycles. Next, we present two novel types of reversibly dye-labeled nucleotide analogues, show that DNA polymerase can incorporate these analogues, and demonstrate that the dyes can be removed by thiol reduction or light exposure. Using these nucleotides, we have sequenced multiple polonies in parallel. In addition, we have found that a high density of polonies can be achieved with minimal overlap between adjacent polonies by limiting the concentration of free primer in the polony amplification reactions. Finally, we have developed software for automated image alignment and sequence calling.     

Paul-Bunnell antigen and a possible mechanism of formation of heterophile antibodies in patients with infectious mononucleosis

Sera of patients with infectious mononucleosis contain heterophile anti-Paul- Bunnell (PB) antibodies to erythrocytes of numerous mammalian species. Evidence is presented that the corresponding antigen of bovine erythrocytes is not, as previously described, a single molecule, but a series of glycoproteins with glycans terminated with N-glycolylneuraminic acid (Neu5Gc). The latter compound should be an important part of the PB epitope because, in agreement with the results of others, we found that desialylation of the PB antigen abolishes almost completely its activity. We examined three different preparations of GM3 ganglioside for their capacity to bind anti-PB and found that only GM3 from horse erythrocytes containing Neu5Gc exhibited a low although ELISA measurable PB activity. The other two GM3 preparations, from bovine milk and dog erythrocytes, containing N-acetylneuraminic acid (Neu5Ac) bound little if any anti-PB antibodies. This finding confirms a previous report that human erythrocyte Neu5Ac containing sialoglycoprotein with similar O-linked glycans as the PB-antigen of bovine erythrocytes exhibits only very low PB activity (Patarca & Fletcher, 1995, Crit Rev Oncogen., 6: 305). In conclusion, we present a hypothesis that anti-PB antibodies in patients with infectious mononucleosis are formed against infection-induced cell membrane glycoconjugates containing highly immunogenic Neu5Gc.     

Novel properties of antimicrobial peptides

Endogenous peptide antibiotics are known as evolutionarily old components of innate immunity. Due to interaction with cell membrane these peptides cause permeabilization of the membrane and lysis of invading microbes. However, some studies proved that antimicrobial peptides are universal multifunctional molecules and their functions extend far beyond simple antibiotics. In this review we present an overview of the general mechanism of action of antimicrobial peptides and discuss some of their additional properties, like antitumour activity, mitogenic activity, role in signal transduction pathways and adaptive immune response.     

The 33 kDa protein of photosystem II is a low-affinity calcium- and lanthanide-binding protein

We have shown that the isolated 33 kDa protein of photosystem II contains one calcium and one lanthanide low-affinity binding site with binding constants (K(D)) on the order of 10(-5) M. Binding of calcium or lanthanides to this site induces conformational changes in the protein that manifest in fluorescence emission spectra of the protein, circular dichroism spectra, and calorimetric thermograms where the phase transitions are shifted to lower temperatures. The role of calcium binding to the 33 kDa protein in the attainment of its native structure and the significance of this interaction for the oxygen evolution process are discussed.