<Emphasis Type="Italic">Xanthium italicum</Emphasis>, <Emphasis Type="Italic">Xanthium strumarium</Emphasis> and <Emphasis Type="Italic">Arctium lappa</Emphasis> as new hosts for <Emphasis Type="Italic">Diaporthe helianthi</Emphasis>

Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm.     

Novel potent apoA-I peptide mimetics that stimulate cholesterol efflux and pre-β particle formation in vitro

Reverse cholesterol transport (RCT) is believed to be the primary mechanism by which HDL and its major protein apoA-I protect against atherosclerosis. Starting from the inactive 22-amino acid peptide representing the consensus sequence of the class A amphipathic helical repeats of apoA-I, we designed novel peptides able to mobilize cholesterol from macrophages in vitro, and to stimulate the formation of ‘nascent HDL’ particles, with potency comparable to the entire apoA-I protein.     

Ischemia dysregulates DNA methyltransferases and p16INK4a methylation in human colorectal cancer cells

Epigenetic modifications are involved in the initiation and progression of cancer. Expression patterns and activity of DNA methyltransferases (DNMTs) are strictly controlled in normal cells; however, regulation of these enzymes is lost in cancer cells due to unknown reasons. Cancer therapies which target DNMTs are promising treatments of hematologic cancers, but they lack effectiveness in solid tumors. Solid tumors exhibit areas of hypoxia and hypoglycaemia due to their irregular and dysfunctional vasculature, and we previously showed that hypoxia reduces global DNA methylation. Colorectal carcinoma (CRC) cells (HCT116 and 379.2; p53^+/+ and p53^-/-, respectively) were subjected to ischemia (hypoxia and hypoglycaemia) in vitro and levels of DNMTs were assessed. We found a significant decrease in mRNA for DNMT1, DNMT3a and DNMT3b, and similar reductions in DNMT1 and DNMT3a protein levels were detected by western blotting. In addition, total activity levels of DNMTs (as measured by an ELISA-based DNMT activity assay) were reduced in cells exposed to hypoxic and hypoglycaemic conditions. Immunofluorescence of HCT116 tumor xenografts demonstrated an inverse relationship between ischemia (as revealed by carbonic anhydrase IX staining) and DNMT1 protein. Bisulfite sequencing of the proximal promoter region of p16^INK4a showed a decrease in 5-methylcytosine following in vitro exposure to ischemia. These studies provide evidence for the downregulation of DNMTs and modulation of methylation patterns by hypoxia and hypoglycaemia in human CRC cells, both in vitro and in vivo. Our findings suggest that ischemia, either intrinsic or induced through the use of anti-angiogenic drugs, may influence epigenetic patterning and hence tumor progression.Key words: DNA methylation, DNA methyltransferases, colorectal carcinoma, ischemia, p53, hypoxia, hypoglycaemia     

Muskrat (Ondatra zibethicus) decline after the expansion of American mink (Neovison vison) in Poland

Field survey data in Central Poland revealed that the proportion of sites inhabited by muskrats decreased from 44% to 7% over one decade. This corresponded to the decline in hunting bags of muskrat over the whole of Poland. The largest hunting harvest of muskrat was recorded in 1987/1988 (66,416 individuals), the smallest in 2007/2008 (4,567 individuals). The decline in hunting bags occurred in all regions analysed; however, it was most rapid in the north and north-east. Before the expansion of mink, which started in northern Poland at the beginning of the 1980s, muskrat densities in particular regions depended on the availability of aquatic habitats. A comparison of hunting bags of muskrat and American mink in years 2002–2008 indicated a significant negative correlation between the numbers of these two species harvested in seven regions of Poland. The negative correlation between numbers of muskrat and mink suggests that mink predation is one of the most important factors in the decline of the muskrat population in Poland.     

Copper binding to chicken and human prion protein amylodogenic regions: Differences and similarities revealed by Ni as a diamagnetic probe

Both human (h) and chicken (Ch) prion proteins (PrP) bind copper ions within the so called “tandem repeat” N-terminal region. Outside this region, hPrP possesses two additional copper binding sites, localized at His-96 and His-111 in the so called “amylodogenic” or neurotoxic region (residues 91-126). Also ChPrP possesses a similar region (ChPrP_105−140) containing two His (His-110 and His-124) and an identical hydrophobic tail of 15 amino acids rich in Ala and Gly. The copper binding abilities within such region of ChPrP were investigated by NMR, CD and potentiometry using Ni²⁺ as diamagnetic probe. The formation of diamagnetic metal complexes allowed to monitor the chemical shift and signal intensity variations and to determine the structural and kinetic features of the His-110 and His-124 metal binding sites. Finally a comparison between the hPrP and ChPrP metal binding abilities was performed. We found that the two prion proteins exhibited different copper and nickel preferences with the favoured metal binding sites localized at opposite His: His-110 for ChPrP, and His-111 for hPrP.     

Impact of a small cormorant (Phalacrocorax carbo sinensis) roost on nutrients and phytoplankton assemblages in the littoral regions of a submontane reservoir

Cormorants (median numbers of 54.5 ind.) excreted ca. 102.7 kg yr⁻¹ of nitrogen and ca. 80.5 kg yr⁻¹ of phosphorus in the area of the Dobczyce Reservoir (ca. 980 ha). Concentrations of N-tot and P-tot were 3 times higher in soil from the roosting area of the cormorants than outside this area. Nutrient concentrations in the littoral sediment of the reservoir were also higher in the area frequented by these birds. Differences in concentrations of pH, NO₃⁻, NO₂⁻, NH₄⁺, PO₄⁻, and P-tot in water between the area associated with the cormorants and the reference site were not found. Differences in the planktonic algal communities from around the roost and the reference site were not found, with the exception of the chlorophytes which were more abundant in the area occupied by the cormorants. Water movement and mixing in the reservoir can influence the effect of the nutrient load on the water chemistry and planktonic algae.     

Effect of maternal diet rich in omega‐6 and omega‐9 fatty acids on the liver of LDL receptor‐deficient mouse offspring

BACKGROUND: Omega‐6 fatty acids are important to fetal development. However, during gestation/lactation, these fatty acids may contribute toward the development of fat tissue. Omega‐9 fatty acids are associated with a reduction in serum lipids and protection from liver disease. OBJECTIVES: The present study investigated the effect of the maternal intake of omega‐6 and omega‐9 in hypercholesterolemic mothers on the liver of the offspring. METHODS: LDL receptor–deficient mice were fed a diet rich in either omega‐6 (E6D) or omega‐9 (E9D) for 45 days prior to mating and until the birth of the offspring, evaluating the effect on the offspring liver in comparison to a standard diet (STD). RESULTS: Mothers fed with the E6D experienced an increase in total cholesterol (TC) and the offspring exhibited an increase in TC, hepatic triglycerides (TG), and CC‐chemokine ligand (CCL)2/monocyte chemoattractant protein (MCP)‐1 as well as a reduction in HDL. Histological analysis on this group revealed steatosis, leukocyte infiltrate, and increased CCL2/MCP‐1 expression. The ultrastructural analysis revealed hepatocytes with lipid droplets and myofibroblasts. The offspring of mothers fed the standard diet exhibited low serum TC, but microvesicular steatosis was observed. The offspring of mothers fed the E9D exhibited lower serum and hepatic TG as well as higher LDL in comparison to the other diets. The histological analyses revealed lower steatosis and leukocyte infiltrate. CONCLUSIONS: The findings suggest that hypercholesterolemic mothers with a diet rich in omega‐6 fatty acids predispose their offspring to steatohepatitis, whereas a diet rich in omega‐9 has a protective effect. Birth Defects Res (Part B) 89:164–170, 2010. © 2010 Wiley‐Liss, Inc.     

Copper Concentration in Body Tissues and Fluids in Normal Subjects of Southern Poland

Data on the concentration of the elements in the human body are important, for example, to estimate the amounts required to maintain a good healthy state or find their connections with morbidity and mortality. In this paper, the concentration of copper (by flame atomic absorption spectrometry) in material obtained from autopsy cases of nonpoisoned people (n = 130), aged from 14 to 80 years, between 1990–2006, is presented. The following values were found (mean ± SD in micrograms of copper per gram or per milliliter): brain 3.32 ± 1.50 (n = 43), liver 3.47 ± 1.51 (n = 79), kidney 2.15 ± 0.90 (n = 76), stomach 1.10 ± 0.76 (n = 65), intestines 1.54 ± 1.19 (n = 25), lung 1.91 ± 1.30 (n = 27), spleen 1.23 ± 0.28 (n = 3), heart 3.26 ± 0.59 (n = 5), bile 3.60 ± 1.67 (n = 13), and blood 0.85 ± 0.19 (n = 73).     

Potential role of annexin AnnAt1 from Arabidopsis thaliana in pH-mediated cellular response to environmental stimuli

Plant annexins, Ca(2+)- and membrane-binding proteins, are probably implicated in the cellular response to stress resulting from acidification of cytosol. To understand how annexins can contribute to cellular ion homeostasis, we investigated the pH-induced changes in the structure and function of recombinant annexin AnnAt1 from Arabidopsis thaliana. The decrease of pH from 7.0 to 5.8 reduced the time of the formation of ion channels by AnnAt1 in artificial lipid membranes from 3.5 h to 15-20 min and increased their unitary conductance from 32 to 63 pS. These changes were accompanied by an increase in AnnAt1 hydrophobicity as revealed by hydrophobicity predictions, by an increase in fluorescence of 2-(p-toluidino)naphthalene-6-sulfonic acid (TNS) bound to AnnAt1 and fluorescence resonance energy transfer from AnnAt1 tryptophan residues to TNS. Concomitant lipid partition of AnnAt1 at acidic pH resulted in its partial protection from proteolytic digestion. Secondary structures of AnnAt1 determined by circular dichroism and infrared spectroscopy were also affected by lowering the pH from 7.2 to 5.2. These changes were characterized by an increase in beta-sheet content at the expense of alpha-helical structures, and were accompanied by reversible formation of AnnAt1 oligomers as probed by ultracentrifugation in a sucrose gradient. A further decrease of pH from 5.2 to 4.5 or lower led to the formation of irreversible aggregates and loss of AnnAt1 ionic conductance. Our findings suggest that AnnAt1 can sense changes of the pH milieu over the pH range from 7 to 5 and respond by changes in ion channel conductance, hydrophobicity, secondary structure of the protein and formation of oligomers. Further acidification irreversibly inactivated AnnAt1. We suggest that the pH-sensitive ion channel activity of AnnAt1 may play a role in intracellular ion homeostasis.