ppGpp-Dependent Negative Control of DNA Replication of Shiga Toxin-Converting Bacteriophages in Escherichia coli

The pathogenicity of enterohemorrhagic Escherichia coli (EHEC) strains depends on the production of Shiga toxins that are encoded on lambdoid prophages. Effective production of these toxins requires prophage induction and subsequent phage replication. Previous reports indicated that lytic development of Shiga toxin-converting bacteriophages is inhibited in amino acid-starved bacteria. However, those studies demonstrated that inhibition of both phage-derived plasmid replication and production of progeny virions occurred during the stringent as well as the relaxed response to amino acid starvation, i.e., in the presence as well as the absence of high levels of ppGpp, an alarmone of the stringent response. Therefore, we asked whether ppGpp influences DNA replication and lytic development of Shiga toxin-converting bacteriophages. Lytic development of 5 such bacteriophages was tested in an E. coli wild-type strain and an isogenic mutant that does not produce ppGpp (ppGpp⁰). In the absence of ppGpp, production of progeny phages was significantly (in the range of an order of magnitude) more efficient than in wild-type cells. Such effects were observed in infected bacteria as well as after prophage induction. All tested bacteriophages formed considerably larger plaques on lawns formed by ppGpp⁰ bacteria than on those formed by wild-type E. coli. The efficiency of synthesis of phage DNA and relative amount of lambdoid plasmid DNA were increased in cells devoid of ppGpp relative to bacteria containing a basal level of this nucleotide. We conclude that ppGpp negatively influences the lytic development of Shiga toxin-converting bacteriophages and that phage DNA replication efficiency is limited by the stringent control alarmone.     

A review of the genus Archipines Strohecker (Coleoptera: Endomychidae), with descriptions of new taxa and immature stages of Archipines championi Gorham

World species of the genus Archipines are reviewed, keyed and illustrated. The following new synonyms are proposed: Archipines championi (Gorham, 1889) [=Archipines multinotata (Pic, 1929)]; Archipines exsanguis (Gerstaecker, 1858) [=Archipines quadrimaculata (Pic, 1928)]; Archipines flavida (Pic, 1928) [=Archipines grandis Strohecker, 1957]. Lectotypes are designated for Phalantha championi Gorham, Ph. intricata Gorham, Ph. pictipennis Gorham and Ph. variegata Gorham. Four new species: Archipines oberthuri (Brazil), A. unicolor (Brazil), A. macromaculata (Peru), A. peruviensis (Peru) and two new subspecies: A. exsanguis sanestebani (Venezuela), A. apicicornis fairmairei (Peru) are described. The immature stages (mature larva and pupa) of A. championi are described and illustrated. Distribution, nomenclatural history and diagnoses are provided for each species.     

Effect of osmotic stress on the formation of a population of polysomes and their stability in pea (<Emphasis Type="Italic">Pisum sativum</Emphasis> L.) seeds

Plants growing under natural conditions are constantly exposed to various stress factors, which can restrain their productivity and limit yields. This paper deals with the effect of long- and short-term osmotic stress followed by recovery on the formation of polysomes and their stability during germination of pea (Pisum sativum L.) seeds. By isolating polysomes, it is possible to obtain an index which evidences the ability of tissues to synthesize proteins. Changes in the distribution of polysomes often precede measurable changes in amounts of proteins. Under osmotic stress, the dominant population of polysomes was the population of free polysomes (FP). The share of membrane-bound polysomes (MBP) and cytoskeleton-bound polysomes (CBP) and cytoskeleton-membrane-bound polysomes (CMBP) in the total fraction of ribosomes increased under intensive (−1.0 and −1.5 MPa) osmotic stress. These results can suggest that the bound forms of polysomes play an important role in the synthesis of stress proteins. In addition, the stability of polysomes isolated from pea early seedlings growing under unstressed control and osmotic stress conditions was tested. It turned out that polysomes formed under osmotic stress conditions (especially the CMBP) were more resistant to the activity of exogenous ribonucleases than the polysomes in the control samples. Under stress conditions it is highly likely that ribosomes become more densely packed on mRNA thus making it more resistant to ribonuclease. This is just one of the many mechanisms regulating stability of mRNA.     

<Emphasis Type="Italic">MUTYH</Emphasis> Tyr165Cys, <Emphasis Type="Italic">OGG1</Emphasis> Ser326Cys and <Emphasis Type="Italic">XPD</Emphasis> Lys751Gln polymorphisms and head neck cancer susceptibility: a case control study

In the present study we investigated the association between three polymorphisms of the MUTYH (Tyr165Cys, rs34612342), the OGG1 (Ser326Cys, rs1052133) and the XPD (Lys751Gln, rs13181) genes with head and neck cancer risk. Genotypes were determined in DNA from peripheral blood lymphocytes of 265 patients with head and neck squamous cell carcinoma (HNSCC) as well as 280 cancer-free controls by PCR-restriction fragment lenght polymorphisms. We found an association between HNSCC and the Ser326Cys (OR 1.69; 95% CI 1.19–2.45) as well as Cys326Cys (OR 4.56; 95% CI 2.07–10.05) variants of the OGG1 gene. The gene–gene interaction between MUTYH and OGG1 as well as OGG1 and XPD polymorphic variants may contribute to higher prevalence of HNSCC. We also found an association between Ser326Cys and Cys326Cys variants of OGG1 gene and smoking status in HNSCC patients (OR 1.97; 95% CI 1.25–3.11), (OR 3.54; 95% CI 1.39–9.04), respectively. Moreover, we also observed a protective association between Tyr165Cys variant of the MUTYH gene and non-smoking status in HNSCC (OR 0.34; 95% CI 0.17–0.66). We also found a link between gene–gene interaction (MUTYH and OGG1 or OGG1 and XPD) and smoking (ORs 2.17–4.20 and 2.18–5.23) or non-smoking status (ORs 0.11 and 7.61) in HNSCC patients, respectively. In conclusion our data showed that the Ser326Cys polymorphism of the OGG1 gene may modify the risk of HNSCC associated with smoking. Finally we suggested that this polymorphism might be used as predictive factor for head and neck cancer in Polish population.     

Determination of amino acids in saliva using capillary electrophoresis with fluorimetric detection

In the present study a sensitive method for the quantification of main free amino acids in saliva using capillary electrophoresis with laser induced fluorescence detection was developed. As background electrolyte 20 mM borate buffer pH 9.5 was used. Amino acids were separated after derivatization were optimized. The main amino acids occurring in saliva (Pro, Ser, Gly and Glu) were separated in less than 7 min. The parameters of validation such as linearity of response, precision and detection limits were determined. The detection limits were obtained in the range from 0.1 to 2.4 nM. The developed method was employed for determination of amino acids in real saliva samples.     

Delta-Opioid Receptor Analgesia Is Independent of Microglial Activation in a Rat Model of Neuropathic Pain

The analgesic effect of delta-opioid receptor (DOR) ligands in neuropathic pain is not diminished in contrast to other opioid receptor ligands, which lose their effectiveness as analgesics. In this study, we examine whether this effect is related to nerve injury-induced microglial activation. We therefore investigated the influence of minocycline-induced inhibition of microglial activation on the analgesic effects of opioid receptor agonists: morphine, DAMGO, U50,488H, DPDPE, Deltorphin II and SNC80 after chronic constriction injury (CCI) to the sciatic nerve in rats. Pre-emptive and repeated administration of minocycline (30 mg/kg, i.p.) over 7 days significantly reduced allodynia and hyperalgesia as measured on day 7 after CCI. The antiallodynic and antihyperalgesic effects of intrathecally (i.t.) administered morphine (10–20 µg), DAMGO (1–2 µg) and U50,488H (25–50 µg) were significantly potentiated in rats after minocycline, but no such changes were observed after DPDPE (10–20 µg), deltorphin II (1.5–15 µg) and SNC80 (10–20 µg) administration. Additionally, nerve injury-induced down-regulation of all types of opioid receptors in the spinal cord and dorsal root ganglia was not influenced by minocycline, which indicates that the effects of opioid ligands are dependent on other changes, presumably neuroimmune interactions. Our study of rat primary microglial cell culture using qRT-PCR, Western blotting and immunocytochemistry confirmed the presence of mu-opioid receptors (MOR) and kappa-opioid receptors (KOR), further we provide the first evidence for the lack of DOR on microglial cells. In summary, DOR analgesia is different from analgesia induced by MOR and KOR receptors because it does not dependent on injury-induced microglial activation. DOR agonists appear to be the best candidates for new drugs to treat neuropathic pain.     

An iron fist in a velvet glove: The cooperation of a novel pyoverdine from Pseudomonas donghuensis P482 with 7-hydroxytropolone is pivotal for its antibacterial activity

Pseudomonas donghuensis P482 exhibits broad antimicrobial activity against phytopathogens, including the soft rot bacteria of the Dickeya genus. Here, we report that under limited nutrient availability, the antibacterial activity of P. donghuensis P482 against Dickeya solani requires the reciprocal action of two iron scavengers: 7-hydroxytropolone (7-HT) and a newly characterized pyoverdine (PVD_P482) and is quenched in the iron-augmented environment. Further, we show that the biosynthesis of pyoverdine and 7-HT is metabolically coordinated, and the functional BV82_4709 gene involved in 7-HT synthesis is pivotal for expressing the BV82_3755 gene, essential for pyoverdine biosynthesis and vice versa. The synthesis of both scavengers is under the control of Gac/Rsm, but only PVD is controlled by Fur. The isoelectric focusing profile of the P482 siderophore differs from that of the other Pseudomonas spp. tested. This finding led to the unveiling of the chemical structure of the new pyoverdine PVD_P482. To summarize, the antibacterial activity of P. donghuensis P482 is attributed to 7-HT and PVD_P482 varies depending on the nutrient and iron availability, highlighting the importance of these factors in the competition between P482 and D. solani.     

A review of the genus Erotendomychus Lea (Coleoptera: Endomychidae)

Species of the Australian genus Erotendomychus are reviewed. The following new species are described and illustrated: E. dentatus, dorrigo, elongatus, emarginatus, erectus, joalah, kirrama, leai, micropunctatus, micrus, ovatus, peckorum, yeatesi. Nomenclatural history, diagnoses and distribution are provided for each species. A key to the species of the genus is presented.     

The Content of Mercury in Herbal Dietary Supplements

Biological Trace Element Research - The dietary supplement market in Poland has been growing rapidly, and the number of registered products and their consumption increases steadily. Among the most...     

Treatment with TNF-α and IFN-γ alters the activation of SER/THR protein kinases and the metabolic response to IGF-I in mouse c2c12 myogenic cells

The aim of this study was to compare the effects of TNF-α, IL-1β and IFN-γ on the activation of protein kinase B (PKB), p70^S6k, mitogen-activated protein kinase (MAPK) and p90 ^rsk , and on IGF-I-stimulated glucose uptake and protein synthesis in mouse C2C12 myotubes. 100 nmol/l IGF-I stimulated glucose uptake in C2C12 myotubes by 198.1% and 10 ng/ml TNF-α abolished this effect. Glucose uptake in cells differentiated in the presence of 10 ng/ml IFN-γ increased by 167.2% but did not undergo significant further modification upon the addition of IGF-I. IGF-I increased the rate of protein synthesis by 249.8%. Neither TNF-α nor IFN-γ influenced basal protein synthesis, but both cytokines prevented the IGF-I effect. 10 ng/ml IL-1β did not modify either the basal or IGF-I-dependent glucose uptake and protein synthesis. With the exception of TNF-α causing an 18% decrease in the level of PKB protein, the cellular levels of PKB, p70^S6k, p42^MAPK, p44^MAPK and p90 ^rsk were not affected by the cytokines. IGF-I caused the phosphorylation of PKB (an approximate 8-fold increase above the basal value after 40 min of IGF-I treatment), p42^MAPK (a 2.81-fold increase after 50 min), and the activation of p70^S6k and p90 ^rsk , manifesting as gel mobility retardation. In cells differentiated in the presence of TNF-α or IFN-γ, this IGF-I-mediated PKB and p70^S6k phosphorylation was significantly diminished, and the increase in p42^MAPK and p90 ^rsk phosphorylation was prevented. The basal p42^MAPK phosphorylation in C2C12 cells treated with IFN-γ was high and comparable with the activation of this kinase by IGF-I. Pretreatment of myogenic cells with IL-1β did not modify the IGF-I-stimulated phosphorylation of PKB, p70^S6k, p42^MAPK and p90 ^rsk . In conclusion: i) TNF-α and IFN-γ, but not IL-1β, if present in the extracellular environment during C2C12 myoblast differentiation, prevent the stimulatory action of IGF-I on protein synthesis. ii) TNF-α- and IFN-γ-induced IGF-I resistance of protein synthesis could be associated with the decreased phosphorylation of PKB and p70^S6k. iii) The activation of glucose uptake in C2C12 myogenic cells treated with IFN-γ is PKB independent. iv) The similar effects of TNF-α and IFN-γ on the signalling and action of IGF-I on protein synthesis in myogenic cells could suggest the involvement of both of these cytokines in protein loss in skeletal muscle.