The post-glacial sediments of Øvre Heimdalsvatn

Two sediment cores, 143 cm and 268 cm in length, have been investigated. The oldest dating is 8240 ± 500 radiocarbon years B.P. The variation in the composition of the sediments is probably caused solely by climatic changes. The organic fraction is small, never exceeding 20%, reflecting the low primary production and rapid decomposition of allochthonous organic matter within the lake. The proportions of inorganic constituents indicate that the mineral fraction consists of clay and silt particles flushed into the lake from the drainage area.     

Human gastric glycosphingolipids recognized by Helicobacter pylori vacuolating cytotoxin VacA

Many bacterial toxins utilize cell surface glycoconjugate receptors for attachment to target cells. In the present study the potential carbohydrate binding of Helicobacter pylori vacuolating cytotoxin VacA was investigated by binding to human gastric glycosphingolipids on thin-layer chromatograms. Thereby a distinct binding of the toxin to two compounds in the non-acid glycosphingolipid fraction was detected. The VacA-binding glycosphingolipids were isolated and characterized by mass spectrometry and proton NMR as galactosylceramide (Galbeta1Cer) and galabiosylceramide (Galalpha4Galbeta1Cer). Comparison of the binding preferences of the protein to reference glycosphingolipids from other sources showed an additional recognition of glucosylceramide (Glcbeta1Cer), lactosylceramide (Galbeta4Glcbeta1Cer) and globotriaosylceramide (Galalpha4Galbeta4Glcbeta1Cer). No binding to the glycosphingolipids recognized by the VacA holotoxin was obtained with a mutant toxin with deletion of the 37 kDa fragment of VacA (P58 molecule). Collectively our data show that the VacA cytotoxin is a glycosphingolipid binding protein, where the 37 kDa moiety is required for carbohydrate recognition. The ability to bind to short chain glycosphingolipids will position the toxin close to the cell membrane, which may facilitate toxin internalization.     

An epidemiological study of reproductive function biomarkers in male welders

In a cross-sectional study, the serum concentrations of inhibin B and prolactin of 96 male current welders were compared with the concentrations measured in 96 age-matched referents. Also, 23 patients who were all former welders diagnosed as having welding-related manganism were studied. The current welders' geometric mean (GM) airborne exposure to manganese (Mn) was 121 µg m^-3 (range 7-2320). The serum concentrations of prolactin adjusted for age and smoking habits (GM 193 mIU l^-1 vs. 166 mIU l^-1; p=0.047) and inhibin B adjusted for alcohol consumption (arithmetic mean (AM) 151 ng l^-1 vs. 123 ng l^-1; p=0.001) were higher in the welders compared with the referents. The whole blood Mn concentration was associated with the serum prolactin concentrations. Tobacco smoking resulted in lower serum prolactin concentrations. The GM serum prolactin concentrations of the patients did not significantly differ from that of the referents, but their AM serum inhibin B concentration was statistically significantly lower. The results may suggest an effect of Mn on the pituitary that is reversible upon cessation of exposure. Lower inhibin B concentrations in the patients could point to a functional impairment of the testicular Sertoli cells, that may be caused by a welding fume component or other factors in their work environment.     

Examination of Changes in Enzyme Activities of Erythrocyte Glucose 6‐Phosphate Dehydrogenase and 6‐Phosphogluconate Dehydrogenase in Rats Given Naringenin and Lead Acetate

In our study, controlled experimental groups were performed by giving substances Lead acetate, Naringenin and Naringenin + Lead acetate to rats in vivo conditions Changes in the glucose 6‐phosphate dehydrogenase (G6PD) and 6‐phosphogluconate dehydrogenase (6PGD) enzyme activities in erythrocytes of rats in these groups were compared to the Control group. An inhibition significant degree for G6PD enzyme activity was observed in all groups when compared to the Control group (p < 0.001). While inhibition significant degree for 6PGD enzyme activity was observed in Lead acetate groups (p < 0.001), no significant effect was observed in the Naringenin and Naringenin + Lead acetate groups (p > 0.05). In addition, lead levels in the groups of rats were determined using an inductively coupled plasma mass spectrometer (ICP‐MS) device. As a result of measurements by the ICP‐MS device, lead levels were found as an average of 42.9 ± 2.51, 36.71 ± 1.13, 172.16 ± 9.63, and 95.07 ± 5.87 ppm in the Control, Naringenin, Lead acetate and Naringenin + Lead acetate groups, respectively. Our results were shown that Naringenin has protective effects on the Lead acetate induced oxidative stress erythrocytes in rat.     

Salivaricin D, a novel intrinsically trypsin-resistant lantibiotic from Streptococcus salivarius 5M6c isolated from a healthy infant

In this work, we purified and characterized a newly identified lantibiotic (salivaricin D) from Streptococcus salivarius 5M6c. Salivaricin D is a 34-amino-acid-residue peptide (3,467.55 Da); the locus of the gene encoding this peptide is a 16.5-kb DNA segment which contains genes encoding the precursor of two lantibiotics, two modification enzymes (dehydratase and cyclase), an ABC transporter, a serine-like protease, immunity proteins (lipoprotein and ABC transporters), a response regulator, and a sensor histidine kinase. The immunity gene (salI) was heterologously expressed in a sensitive indicator and provided significant protection against salivaricin D, confirming its immunity function. Salivaricin D is a naturally trypsin-resistant lantibiotic that is similar to nisin-like lantibiotics. It is a relatively broad-spectrum bacteriocin that inhibits members of many genera of Gram-positive bacteria, including the important human pathogens Streptococcus pyogenes and Streptococcus pneumoniae. Thus, Streptococcus salivarius 5M6c may be a potential biological agent for the control of oronasopharynx-colonizing streptococcal pathogens or may be used as a probiotic bacterium.     

Borrelia burgdorferi sensu lato in Ixodes ricinus ticks from Norway: evaluation of a PCR test targeting the chromosomal flaB gene

A consensus TaqMan real-time PCR test targeting the chromosomal flaB gene of Borrelia burgdorferi sensu lato was constructed. The test was compared with a recently published generic Light Upon eXtension (LUX) 16S rRNA real-time PCR test (Wilhelmsson et al. in J Clin Microbiol 48:4169–4176, 2010) on material consisting of 242 Ixodes ricinus ticks collected from dogs and cats in Northern Norway (n?=?139) and Telemark County in Southern Norway (n?=?103). Ticks positive in either test were further tested by nested PCR amplification of the 5S-23S rRNA intergenic-spacer region followed by sequencing for species identification. A tick was defined as Borrelia positive if two of three tests were positive. Thirty-four of the 242 (14?%) ticks satisfied this definition of positivity. Of these ticks 32 were positive both in the rRNA and flaB test, while two were positive only in the rRNA test. One tick was positive only in the rRNA test and was considered false positive since PCR for sequencing failed. The sensitivity of the flaB test was 94?% and the specificity 100?%. It was possible to determine the species present using Tm analysis. Among ticks from Northern Norway the prevalence of Borrelia was 13?%, whereas the prevalence in Telemark was 16?%. Among identified species (n?=?33) B. afzelii was found in 16 (47?%), B. garinii in 15 (44?%) and B. valaisiana in 2 (6?%) ticks, respectively. The flaB test is a rapid, sensitive and specific test for detection and quantification of Borrelia burgdorferi s.l. in I. ricinus ticks. This is the first report on Borrelia prevalence in I. ricinus in Northern Norway.     

Effects of changes in ambient PAR and UV radiation on the nutritional quality of an Arctic diatom (Thalassiosira antarctica var. borealis)

Polyunsaturated fatty acids (PUFAs) are essential macromolecules that are synthesized by phytoplankton during spring bloom, and they play a key role in the Arctic food web. They are, however, considered to be sensitive to oxidation by UV radiation (280-400 nm). Changes in the food quality of primary producers may affect the transport of biomass and energy in the whole ecosystem. Using a common Arctic diatom, we looked at the effect of ambient and increased UV radiation on its nutritional quality, specifically, the fatty acid composition and elemental ratios. In May 2004, in the archipelago of Svalbard (79° N), a unialgal culture of Thalassiosira antarctica var. borealis was subjected to a 17-day experiment in outdoor aquaria. The diatoms were kept in semi-continuous culture (40 1) and exposed to three treatments with different levels of UV radiation: none (UV-shielded), ambient, and enhanced. Fatty acid composition, C:N:P ratios, photosynthetic pigment composition, optimum quantum yield of PSII, and cell numbers were analysed over the experimental period. An initial increase in PAR (photosynthetically active radiation, 400-700 nm) intensities profoundly affected the fatty acid composition and substantially inhibited the synthesis of PUFAs, but the relative amounts of PUFAs were not reduced by UV radiation. Enhanced UV radiation did, however, cause a significant reduction in optimum quantum yield of PSII and affected some fatty acids, mainly 18:0 and 16:1 n-7, during the first week of the experiment. Both ambient and enhanced UV radiation caused significantly lower C:P and N:P ratios. At the same time, these treatments elicited a higher relative content of the photoprotective pigments diadinoxanthin and diatoxanthin. After acclimation to the new light levels these effects faded off. Thus, brief periods with high light exposure may cause significant changes in photosynthetic activity and food quality, but the capacity for photo-acclimation seems high. The impact of UV radiation seems to be less important for food quality than that of PAR during a sudden rise in total light intensity.     

Complete lipopolysaccharide of Plesiomonas shigelloides O74:H5 (strain CNCTC 144/92). 1. Structural analysis of the highly hydrophobic lipopolysaccharide, including the O-antigen, its biological repeating unit, the core oligosaccharide, and the linkage between them

The lipopolysaccharide of Plesiomonas shigelloides serotype O74:H5 (strain CNCTC 144/92) was obtained with the hot phenol/water method, but unlike most of the S-type enterobacterial lipopolysaccharides, the O-antigens were preferentially extracted into the phenol phase. The poly- and oligosaccharides released by mild acidic hydrolysis of the lipopolysaccharide from both phenol and water phases were separated and investigated by (1)H and (13)C NMR spectroscopy, MALDI-TOF mass spectrometry, and sugar and methylation analysis. The O-specific polysaccharide and oligosaccharides consisting of the core, the core with one repeating unit, and the core with two repeating units were isolated. It was concluded that the O-specific polysaccharide is composed of a trisaccharide repeating unit with the [-->2)-beta-d-Quip3NAcyl-(1-->3)-alpha-l-Rhap2OAc-(1-->3)-alpha-d-FucpNAc-(1-->] structure, in which d-Qui3NAcyl is 3-amino-3,6-dideoxy-d-glucose acylated with 3-hydroxy-2,3-dimethyl-5-oxopyrrolidine-2-carboxylic acid. The major oligosaccharide consisted of a single repeating unit and a core oligosaccharide. This undecasaccharide contains information about the biological repeating unit and the type and position of the linkage between the O-specific chain and core. The presence of a terminal beta-d-Quip3NAcyl-(1--> residue and the -->3)-beta-d-FucpNAc-(1-->4)-alpha-d-GalpA element showed the structure of the biological repeating unit of the O-antigen and the substitution position to the core. The -->3)-beta-d-FucpNAc-(1--> residue has the anomeric configuration inverted compared to the same residue in the repeating unit. The core oligosaccharide was composed of a nonphosphorylated octasaccharide, which represents a novel core type of P. shigelloides LPS characteristic of serotype O74. The similarity between the isolated O-specific polysaccharide and that found on intact bacterial cells and lipopolysaccharide was confirmed by HR-MAS NMR experiments.     

Specific Degradation of the Mucus Adhesion-Promoting Protein (MapA) of Lactobacillus reuteri to an Antimicrobial Peptide

The intestinal flora of mammals contains lactic acid bacteria (LAB) that may provide positive health effects for the host. Such bacteria are referred to as probiotic bacteria. From a pig, we have isolated a Lactobacillus reuteri strain that produces an antimicrobial peptide (AMP). The peptide was purified and characterized, and it was unequivocally shown that the AMP was a well-defined degradation product obtained from the mucus adhesion-promoting protein (MapA); it was therefore termed AP48-MapA. This finding demonstrates how large proteins might inherit unexpected pleiotropic functions by conferring antimicrobial capacities on the producer. The MapA/AP48-MapA system is the first example where a large protein of an intestinal LAB is shown to give rise to such an AMP. It is also of particular interest that the protein that provides this AMP is associated with the binding of the bacterium producing it to the surface/lining of the gut. This finding gives us new perspective on how some probiotic bacteria may successfully compete in this environment and thereby contribute to a healthy microbiota.Mammals have a microbiota in their digestive tract that contains lactic acid bacteria (LAB). It has been increasingly evident that some of these lactic acid bacteria produce antimicrobial peptides that may contribute to the positive effect on their host. Such bacteria are often referred to as probiotics, and one of their important beneficial effects is their ability to produce antimicrobial compounds that prevent or interfere with the growth of pathogenic bacteria in the host.It is known that the fecal microflora of pigs/piglets is large and diverse and develops rapidly after birth. Lactobacillus reuteri is among the very first lactic acid bacteria that colonize the intestine of new-born piglets, and their numbers gradually increase until they become the most dominant LAB in pigs (5, 17, 28). Other lactobacilli that are also part of the gut microbiota of pigs include L. amylovorus, L. acidophilus, L. salivarius, and L. casei (4, 8). Probiotic isolates have been identified within all these species, and many of them are today used as food/feed supplements to support good health (4, 11, 27). An important part of the antimicrobial arsenal produced by lactic acid bacteria (LAB) is a group of peptides called bacteriocins, which are ribosomally synthesized antibiotic-like peptides (antimicrobial peptides [AMPs]) (3, 7, 19). The bacteriocins constitute a wide range of structurally different peptides that are divided into different classes and subclasses. Some are modified (the lantibiotics, or class I), while others are basically unmodified (class II) (3, 6, 19).Most bacteriocins are derived from prepeptides, each containing a short leader sequence (14 to 30 amino acids [aa]) which is cleaved off during the secretion of the mature peptide (19). In recent years, a new group of AMPs have been recognized (18); these are different from regular bacteriocins in that they are derived from larger proteins through specific degradations, leading to a defined peptide possessing antimicrobial activity. Such antimicrobial peptides have been known for a long time in mammalian systems. For instance, lactoferrin, a protein in milk, is readily degraded to a specific antimicrobial peptide through heat, acid treatment, or pepsin digestion (14, 24, 26). Defined histone fragments with antimicrobial properties have been isolated from different eukaryotic species (1, 2, 15, 21, 23), and a few antimicrobial peptides derived from larger proteins have been isolated in bacteria, including Helicobacter pylori (22), propionic acid bacteria (9, 10), and Clostridium beijerinckii (13). Such antimicrobial peptides are most likely formed by proteolytic degradation during cell proliferation or death.