Sublethal injuries in Middle Jurassic ammonite shells from Poland

Sublethal injuries, the effects of which are seen as regeneration patterns, are described from Late Bajocian and Bathonian (Middle Jurassic) ammonites from Poland (Polish Jura area) for the first time. The total number of ammonite shells bearing signs of sublethal injuries is small (only 11 specimens, which constitute ∼1.2% of all ammonites investigated), and this value is even smaller (∼0.3 to 0.8%) when analysing a large sample of a particular ammonite species. Specimens under consideration represent ten species, belonging to six genera and five families. All the healed injuries are represented by only one type, referred to as the ‘forma verticata’ of Hölder. This type of regeneration, very common in ammonite shells in general, is an effect of a puncture injury of the shell-secreting mantle-epithelia at the apertural margin. Although many different extrinsic (mechanical) factors may be responsible for such healed injuries, here it is most plausible they are an effect of either competitive or predatory activities. Other causes, like collision of the ammonite shells with the substrate in a high-energy environment, are excluded because the sea-bottom was soft and situated below the storm wave-base. From many potential predators inhabiting the Polish Basin during the Bajocian and Bathonian, the most likely to have caused these injuries are other ammonites, belemnites and nautiloids. Crabs, which are cited in the literature as a probable perpetrator of the ‘forma verticata’ injuries, appear unlikely here, as the ammonites under discussion were not purely benthic.     

PdhS,an Old-Pole-Localized Histidine Kinase,Recruits the Fumarase FumC in Brucella abortus

The bacterial pathogen Brucella abortus was recently demonstrated to recruit the essential cytoplasmic histidine kinase PdhS to its old pole. Here, we report identification of the fumarase FumC as a specific partner for the N-terminal “sensing” domain of PdhS, using an ORFeome-based yeast two-hybrid screen. We observed that FumC and PdhS colocalize at the old pole of B. abortus, while the other fumarase FumA is not polarly localized. FumC is not required for PdhS localization, and polar FumC localization is not FumA dependent. FumC homologs are not polarly localized in Sinorhizobium meliloti and Caulobacter crescentus, suggesting that polar recruitment of FumC by PdhS is evolutionarily recent.It was previously reported that morphological asymmetry, here defined by the production of two sibling cells different in length at each cell cycle, is a common feature shared by at least four members of the alphaproteobacteria with diversified lifestyles, namely, the free-living model bacterium Caulobacter crescentus, the plant pathogen Agrobacterium tumefaciens, the plant symbiont Sinorhizobium meliloti, and the facultative intracellular pathogen Brucella abortus (5). In B. abortus, an essential cytoplasmic histidine kinase named PdhS is anchored to the old pole of the bacterium (6). PdhS interacts with the response regulator DivK (6).PdhS is a rather atypical histidine kinase. It is cytoplasmic and contains an N-terminal “sensing” domain with no predicted function, except for a PAS domain that remains to be characterized. Nevertheless, the N-terminal part preceding the PAS domain of PdhS is sufficient for polar localization in B. abortus, as well as in the alphaproteobacteria S. meliloti and C. crescentus (6). This suggests that a molecular mechanism and/or polar structure required for PdhS targeting is conserved in these alphaproteobacteria.     

Helicobacter pylori infection can modulate the susceptibility of gastric mucosa cells to MNNG

The pathogenesis of stomach cells can be associated with their susceptibility to exogenous dietary irritants, like nitrosamines such as dimethylnitrosamines (DMNA), and to the effects of non-dietary factors, including Helicobacter pylori infection. We used N-methyl-N’-nitro N-nitrosoguanidyne (MNNG) as a surrogate agent that induces a spectrum of DNA damage similar to DMNA. Using the alkaline comet assay, we showed that antioxidants — vitamins C and E, quercetin, and melatonin — reduced the genotoxic effect of MNNG in H. pylori-infected and non-infected human gastric mucosa cells (GMCs). To compare the sensitivity of the stomach and the blood, the experiment was also carried out in peripheral blood. We observed a higher level of DNA damage induced by MNNG in H. pylori-infected than in noninfected GMCs. We did not note any difference in the efficacy of the repair of the damage in either type of GMC. H. pylori infection may play an important role in the pathogenesis of GMCs, as it can modulate their susceptibility to dietary mutagens/carcinogens, thus contributing to gastric cancer.     

Casein kinases phosphorylate multiple residues spanning the entire hnRNP K length

Heterogeneous Nuclear Ribonucleoprotein K (hnRNP K) is an RNA/DNA-binding protein involved in many processes that regulate gene expression. K protein's pleiotropic action reflects the diversity of its molecular interactions. Many of these interactions have been shown to be regulated by phosphorylation. K protein contains more than seventy potential phosphorylation sites. We used an integrated approach of mass spectrometry and computer analysis to explore patterns of K protein phosphorylation. We found that in vitro a single kinase can phosphorylate K protein on multiple sites spanning the entire length of the protein, including residues contained within the RNA/DNA-binding domains. 2-D gel electrophoresis of K protein purified from cells identified 5-8 spots. Mass spectrometry of K protein isolated from proliferating cells and from cells under oxidative stress revealed the same pattern of phosphopeptides. The structural implications of phosphorylation are discussed.     

Putative cross-kingdom horizontal gene transfer in sponge (Porifera) mitochondria

Background  

The mitochondrial genome of Metazoa is usually a compact molecule without introns. Exceptions to this rule have been reported only in corals and sea anemones (Cnidaria), in which group I introns have been discovered in the cox1 and nad5 genes. Here we show several lines of evidence demonstrating that introns can also be found in the mitochondria of sponges (Porifera).     

Glutathione and GSH-dependent enzymes in patients with liver cirrhosis and hepatocellular carcinoma

We investigated glutathione level, activities of selenium independent GSH peroxidase, selenium dependent GSH peroxidase, GSH S-transferase, GSH reductase and the rate of lipid peroxidation expressed as the level of malondialdehyde in liver tissues obtained from patients diagnosed with cirrhosis or hepatocellular carcinoma. GSH level was found to be lower in malignant tissues compared to adjacent normal tissues and it was higher in cancer than in cirrhotic tissue. Non-Se-GSH-Px activity was lower in cancer tissue compared with adjacent normal liver or cirrhotic tissue, while Se-GSH-Px activity in cancer was found to be similar to its activity in cirrhotic tissue and lower compared to control tissue. An increase in GST activity was observed in cirrhotic tissue compared with cancer tissue, whereas the GST activity in cancer was lower than in adjacent normal tissue. The activity of GSH-R was similar in cirrhotic and cancer tissues, but higher in cancer tissue compared to control liver tissue. An increased level of MDA was found in cancer tissue in comparison with control tissue, besides its level was higher in cancer tissue than in cirrhotic tissue. Our results show that the antioxidant system of cirrhosis and hepatocellular carcinoma is severely impaired. This is associated with changes of glutathione level and activities of GSH-dependent enzymes in liver tissue. GSH and enzymes cooperating with it are important factors in the process of liver diseases development.     

Crystal structure and solid-state 13C NMR analysis of N-o-, N-m- and N-p-nitrophenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylamines, and their N-acetyl derivatives

The X-ray diffraction analysis of N-o-nitrophenyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranosylamine (1), N-m-nitrophenyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranosylamines, N-p-nitrophenyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranosylamines, and their N-acetyl derivatives was performed. The sugar moieties always adopt ⁴C₁ conformations, however, due to crystal packing forces they are always slightly distorted. It was found that except N-acetyl, N-m-nitrophenyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranosylamine (5), none of the glucopyranosylamines studied in this paper form strong hydrogen bonds in the crystal lattice. Additionally, (5) crystallizes with a molecule of water, which occupies a special crystallographic position (on the twofold axis) and links two sugar molecules by hydrogen bonds. The CP MAS NMR spectra confirmed the presence of the intermolecular hydrogen bond involving the molecule of water in (5). Moreover, it was proved that in (1) an intramolecular hydrogen bond is formed between the glycosidic linkage and the nitro group.