Schizosaccharomyces pombe encodes a mutated AP endonuclease 1

Mutagenic and cytotoxic apurinic/apyrimidinic (AP) sites are among the most frequent lesions in DNA. Repair of AP sites is initiated by AP endonucleases and most organisms possess two or more of these enzymes. Saccharomyces cerevisiae has AP endonuclease 1 (Apn1) as the major enzymatic activity with AP endonuclease 2 (Apn2) being an important backup. Schizosaccharomyces pombe also encodes two potential AP endonucleases, and Apn2 has been found to be the main repair activity, while Apn1 has no, or only a limited role in AP site repair. Here we have identified a new 5' exon (exon 1) in the apn1 gene and show that the inactivity of S. pombe Apn1 is due to a nonsense mutation in the fifth codon of this new exon. Reversion of this mutation restored the AP endonuclease activity of S. pombe Apn1. Interestingly, the apn1 nonsense mutation was only found in laboratory strains derived from L972 h(-) and not in unrelated isolates of S. pombe. Since all S. pombe laboratory strains originate from L972 h(-), it appears that all experiments involving S. pombe have been conducted in an apn1(-) mutant strain with a corresponding DNA repair deficiency. These observations have implications both for future research in S. pombe and for the interpretation of previously conducted epistatis analysis.     

From the genome sequence to the protein inventory of Bacillus subtilis

Owing to the low number of proteins necessary to render a bacterial cell viable, bacteria are extremely attractive model systems to understand how the genome sequence is translated into actual life processes. One of the most intensively investigated model organisms is Bacillus subtilis. It has attracted world-wide research interest, addressing cell differentiation and adaptation on a molecular scale as well as biotechnological production processes. Meanwhile, we are looking back on more than 25 years of B. subtilis proteomics. A wide range of methods have been developed during this period for the large-scale qualitative and quantitative proteome analysis. Currently, it is possible to identify and quantify more than 50% of the predicted proteome in different cellular subfractions. In this review, we summarize the development of B. subtilis proteomics during the past 25 years.     

The regulatory subunit of PKA-I remains partially structured and undergoes β-aggregation upon thermal denaturation

Background

The regulatory subunit (R) of cAMP-dependent protein kinase (PKA) is a modular flexible protein that responds with large conformational changes to the binding of the effector cAMP. Considering its highly dynamic nature, the protein is rather stable. We studied the thermal denaturation of full-length RIα and a truncated RIα(92-381) that contains the tandem cyclic nucleotide binding (CNB) domains A and B.

Methodology/Principal Findings

As revealed by circular dichroism (CD) and differential scanning calorimetry, both RIα proteins contain significant residual structure in the heat-denatured state. As evidenced by CD, the predominantly α-helical spectrum at 25°C with double negative peaks at 209 and 222 nm changes to a spectrum with a single negative peak at 212–216 nm, characteristic of β-structure. A similar α→β transition occurs at higher temperature in the presence of cAMP. Thioflavin T fluorescence and atomic force microscopy studies support the notion that the structural transition is associated with cross-β-intermolecular aggregation and formation of non-fibrillar oligomers.

Conclusions/Significance

Thermal denaturation of RIα leads to partial loss of native packing with exposure of aggregation-prone motifs, such as the B'' helices in the phosphate-binding cassettes of both CNB domains. The topology of the β-sandwiches in these domains favors inter-molecular β-aggregation, which is suppressed in the ligand-bound states of RIα under physiological conditions. Moreover, our results reveal that the CNB domains persist as structural cores through heat-denaturation.     

H1-antihistamine up-dosing in chronic spontaneous urticaria: patients' perspective of effectiveness and side effects--a retrospective survey study

Background

The guidelines recommend that first line treatment of chronic spontaneous urticaria should be second generation non-sedating H₁-antihistamines with a positive recommendation against the use of old sedating first generation antihistamines. If standard dosing is not effective, increasing the dosage up to four-fold is recommended. The objective of this study was to obtain the chronic spontaneous urticaria-patient perspective on the effectiveness and unwanted effects of H₁-antihistamines in standard and higher doses.

Methodology/Principal Findings

This was a questionnaire based survey, initially completed by 368 individuals. 319 (248 female, 71 male, median age 42 years) had a physician-confirmed diagnosis of chronic spontaneous urticaria and were included in the results. Participants believed standard doses (manufacturers recommended dose) of second generation antihistamines to be significantly (P<0.005) more effective than first generation drugs. Furthermore, they believed that second generation drugs caused significantly (P<0.001) fewer unwanted effects and caused significantly (P<0.001) less sedation than first generation antihistamines. Three-quarters of the patients stated that they had up-dosed with antihistamines with 40%, 42% and 54% reporting significant added benefit from taking 2, 3 or 4 tablets daily respectively. The number of reports of unwanted effects and sedation following up-dosing were not significantly different from those reported for standard doses.

Conclusions

This survey supports the urticaria guidelines recommendations that the first line treatment for chronic spontaneous urticaria should be second generation rather than first generation H₁-antihistamines and that, if standard dosing is not effective, the dosage should be increased up to four-fold.     

Comparison of accuracy of diabetes risk score and components of the metabolic syndrome in assessing risk of incident type 2 diabetes in Inter99 cohort

Background

Given the increasing worldwide incidence of diabetes, methods to assess diabetes risk which would identify those at highest risk are needed. We compared two risk-stratification approaches for incident type 2 diabetes mellitus (T2DM); factors of metabolic syndrome (MetS) and a previously developed diabetes risk score, PreDx® Diabetes Risk Score (DRS). DRS assesses 5 yr risk of incident T2DM based on the measurement of 7 biomarkers in fasting blood.

Methodology/Principal Findings

DRS was evaluated in baseline serum samples from 4,128 non-diabetic subjects in the Inter99 cohort (Danes aged 30–60) for whom diabetes outcomes at 5 years were known. Subjects were classified as having MetS based on the presence of at least 3 MetS risk factors in baseline clinical data. The sensitivity and false positive rate for predicting diabetes using MetS was compared to DRS. When the sensitivity was fixed to match MetS, DRS had a significantly lower false positive rate. Similarly, when the false positive rate was fixed to match MetS, DRS had a significantly higher specificity. In further analyses, subjects were classified by presence of 0–2, 3 or 4–5 risk factors with matching proportions of subjects distributed among three DRS groups. Comparison between the two risk stratification schemes, MetS risk factors and DRS, were evaluated using Net Reclassification Improvement (NRI). Comparing risk stratification by DRS to MetS factors in the total population, the NRI was 0.146 (p = 0.008) demonstrating DRS provides significantly improved stratification. Additionally, the relative risk of T2DM differed by 15 fold between the low and high DRS risk groups, but only 8-fold between the low and high risk MetS groups.

Conclusions/Significance

DRS provides a more accurate assessment of risk for diabetes than MetS. This improved performance may allow clinicians to focus preventive strategies on those most in need of urgent intervention.     

DISCUSSIONS AROUND A SAND-DRAWING: CREATIONS OF AGENCY AND SOCIETY IN MELANESIA

This article considers the social circumstances of making a marriage diagram, on the island of Ambrym in Vanuatu. It offers a reconsideration of the rather famous case of the 'six-section marriage system' as demonstrated by Cambridge anthropologist Bernard Deacon. It relates this idea of a system to the indigenous practice of making figurative drawings in the sand. The argument is that the marriage diagram drawn for Bernard Deacon was merely an instance of Vanuatu people's institutionalized capability of totalizing social flows and making them into aesthetic shapes.     

INSECT-CYCAD SYMBIOSIS AND ITS RELATION TO THE POLLINATION OF ZAMIA FURFURACEA (ZAMIACEAE) BY RHOPALOTRIA MOLLIS (CURCULIONIDAE)

Zamia furfuracea, a cycad of Mexican origin, in cultivation is pollinated by the snout weevil, Rhopalotria mollis, also of Mexican origin. This weevil apparently is host specific, swarming upon male cones of the cycad, where mating, feeding, and oviposition occur. Sporophylls of male cones are rich in starch; those of female cones are poor in starch, and weevils feed upon male cones and are visitors to but not feeders upon or within female cones. Pollen transport to female cones occurs during such visitation. All stages of metamorphosis of R. mollis occur within male cones; larvae feed exclusively on parenchyma of microsporophylls, pupate within stalks of microsporophylls, and emerge as adults from the outer ends of microsporophylls. They do not feed on pollen and do not damage microsporangia or pollen. Toward the end of the breeding season of the weevil (and the cycad), some larvae enter diapause in thick-walled pupal cases within microsporangial stalks of pollen-spent cones. These remain in diapause until the next reproductive season of the cycad.     

Interaction between left ventricular wall motion and intraventricular flow propagation in acute and chronic ischemia

Myocardial ischemia has been associated with left ventricular (LV) postsystolic shortening. The combination of tissue Doppler imaging and high frame-rate acquisition of two-dimensional color flow makes it possible to study the interaction between LV wall motion and intraventricular flow propagation. The aim of this study was to examine in a clinical model the impact that acute myocardial ischemia and prior myocardial infarct might have on LV flow patterns and to explain the underlying mechanisms from the tissue Doppler data. LV flow propagation and tissue velocities during early diastole were studied in 18 healthy individuals, 17 patients with prior anterior myocardial infarct, and 16 patients before and during percutaneous coronary intervention (PCI) of the left anterior descending artery. Normal individuals had intraventricular flow propagation toward the apex during isovolumic relaxation. During this early diastolic time phase, myocardial velocities measured at mid- and apical septal segment were directed away from the apex. Before PCI, patients without myocardial infarction had similar findings as in normal individuals. In contrast, each patient with either prior myocardial infarction or PCI-induced acute ischemia had flow propagation opposite to normal individuals, and tissue velocities reversed toward the apex during early diastole. Reversal of early diastolic LV flow propagation in acute and chronic anterior myocardial ischemia reflects postsystolic shortening in the dyskinetic apical and septal myocardial segments.