2D-NMR studies of the unnatural duplex alpha-d(TCTAAAC)-beta-d(AGATTTG).

The unnatural oligonucleotide alpha-d(TCTAAAC) was synthesized and was found more resistant towards endonucleases than its beta-analog. 2D-NMR experiments allowed the assignment of all non-exchangeable aromatic and sugar protons except for the overlapping 5' -5" resonances, as well as the exchangeable imino protons of the parallel hybrid duplex alpha-d (TCTAAAC)-beta-d(AGATTTG). NMR studies show that the strength of the association between the alpha-strand and the beta parallel strand is equivalent to that between their anti-parallel complementary beta-analogs beta-d(CAAATCT) and beta-d(AGATTTG). NOE data provide evidence that both duplexes form stable right-helical duplexes with an anti-conformation on the glycosyl linkages and a Watson-Crick pairing. NOESY and COSY spectra allowed us to determine that alpha and beta deoxyriboses adopt a 3' -exo conformation.     

Seasonal and inter-annual variations of nitrogen diagenesis in the sediments of a recently impounded basin

The Méry-sur-Oise (France) storage reservoir is an artificial basin of 9 m average depth, fed by water from the river Oise with a mean residence time of about 4 days. Sediments are accumulating at a rate of about 0.7 cm/month. In the sediments, two fractions of organic nitrogen with different rates of bacterial degradation could be distinguished, one associated with fresh phytoplankton, the other made of detrital and more refractory compounds. The fluxes of oxygen, nitrate and ammonium across the sediment-water interface were measured with a bell-jar system at different seasons during a 3 year period following flooding of the basin. The measurements show clear seasonal variations in relation with the variations of temperature and input of fresh phytoplanktonic material to the sediment. In addition, a long term trend of increasing ammonium was observed. Measurements were also carried out after dredging of all accumulated sediments of the basin. They showed a considerable reduction of the flux of nitrate to the sediments and a significant reduction of the flux of ammonium to the water column.These results are interpreted in the light of a non stationary model of N diagenesis in accumulating sediments. This model is able to predict at least the general trends of benthic N cycling of basins during the early stage of their ecological succession.     

Two-dimensional 1H, 15N NMR investigation of uniformly 15N-labeled lac repressor headpiece.

15N uniformly labeled lac repressor and lac repressor headpiece were prepared. 15N NMR spectra of lac repressor were shown resolution inadequate for detailed study while the data showed that the 15N labeled N-terminal part of the protein is quite suitable for this type of study allowing future investigation of the specific interaction of the lac repressor headpiece with the lac operator. We report here the total assignment of proton 1H and nitrogen 15NH backbone resonances of this headpiece in the free state. Assignments of the 15N resonances of the protein were obtained in a sequential manner using heteronuclear multiple quantum coherence (HMQC), relayed HMQC nuclear Overhauser and relayed HMQC-HOHAHA spectroscopy. More than 80 per cent of residues were assigned by their 15NH(i)-N1H(i + 1) and 15NH(i)-N1H(i - 1) connectivities. Values of the 3JNH alpha splitting for 39 of the 51 residues of the headpiece were extracted from HMQC and HMQC-J. The observed 15NH(i)-C beta H cross peaks and the 3JNH alpha coupling constants values are in agreement with the three alpha-helices previously described [Zuiderweg, E.R.P., Scheek, R.M., Boelens, R., van Gunsteren, W.F. and Kaptein, R., Biochimie 67, 707 (1985)]. The 3JNH alpha coupling constants can be now used for a more confident determination of the lac repressor headpiece. From these values it is shown that the geometry of the ends of the second and third alpha-helices exhibit deviation from the canonical alpha-helix structure. On the basis of NOEs and 3JNH alpha values, the geometry of the turn of the helix-turn-helix motif is discussed.     

Selectively 13C-enriched DNA: 13C and 1H assignments of a triple helix by two-dimensional relayed HMQC experiments

Summary We present NMR studies of an intramolecular triple helix, the three strands of which have been linked by a hexaethylene glycol chain. To overcome the generally encountered difficulties of assignment in the homopyrimidine strands, the carbon C1 of the pyrimidines were selectively ¹³C-enriched. Assignments of the aromatic and sugar protons were obtained from NOESY-HMQC and TOCSY-HMQC spectra. We show that the recognition of a DNA duplex by a third strand via triplex formation is easily carried out in solution by observing the changes of the ¹H1–¹³C1 connectivities as a function of pH. Furthermore, the conformation of the sugars has been found to be C2-endo, on the basis of the coupling constant values directly measured in an HSQC spectrum.     

Biomass and feeding activity of phagotrophic mixotrophs in the northwestern Black Sea during the summer 1995

Biomass and activities of planktonicmicroorganisms (bacteria, nanoplankton andmicroplankton) were measured in the northwestern BlackSea during summer 1995. The method based on theuptake of fluorescently labeled prey was chosen todetermine the ingestion rate of bacteria andnanoplankton by phagotrophic microorganisms. Thismethod revealed the presence of mixotrophic organismssuch as ’plastid-retaining ciliates‘ in the wholecoastal area. Mixotrophic ciliates were dominated bymicro-sized forms and maximum biomasses were recorded inthe water masses characterised by low nutrientconcentrations but high food particle concentrations. Mixotrophic nanoflagellates were absentand mixotrophic dinoflagellates were observed at onestation only. Mixotrophic ciliates were shown to ingestpreferably bacteria while mixotrophic dinoflagellateswere grazing almost exclusively on nanoflagellates.Although the biomass of mixotrophic organisms weresignificantly lower than those of aplastidic protozoa,their feeding activity contributed to 14 and 24% ofthe ingestion of bacteria and nanoplankton, respectively.This is due to the high specificingestion rate of mixotrophic micro-sized ciliates anddinoflagellates, which were two and three times higher,respectively, than the specific ingestion rate ofbacteria and nanoplankton by aplastidic protozoa. Thissuggests a significant contribution of phagotrophicmixotrophs to the microbial network of thenorthwestern Black Sea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Models of interaction between nucleic acids and proteins. Hydrogen bonding of arginine with nucleic acid bases, phosphate groups and carboxylic acids.

Complex formation between the side chain of arginine and nucleic acid bases has been investigated by proton magnetic resonance in dimethylsulfoxide. Simultaneous formation of two hydrogen bonds leads to a selectivity of arginine interaction towards cytosine and guanine. A comparison is made of the interaction of arginine side chain with nucleic acid bases, phosphate and carboxylate anions. It is shown that interaction between carboxylate and arginine is stronger than between phosphate and arginine. These results are discussed with respect to the selective recognition of nucleic acid bases by arginine side chains and by the arginyl-glutamyl ion pair which could form in proteins interacting with nucleic acids.     

Treating Cattle to Protect People? Impact of Footbath Insecticide Treatment on Tsetse Density in Chad

Background

In Chad, several species of tsetse flies (Genus: Glossina ) transmit African animal trypanosomoses (AAT), which represents a major obstacle to cattle rearing, and sleeping sickness, which impacts public health. After the failure of past interventions to eradicate tsetse, the government of Chad is now looking for other approaches that integrate cost-effective intervention techniques, which can be applied by the stake holders to control tsetse-transmitted trypanosomoses in a sustainable manner. The present study thus attempted to assess the efficacy of restricted application of insecticides to cattle leg extremities using footbaths for controlling Glossina m. submorsitans, G . tachinoides and G . f . fuscipes in southern Chad.

Methodology/Principal Findings

Two sites were included, one close to the historical human African trypanosomiasis (HAT) focus of Moundou and the other to the active foci of Bodo and Moissala. At both sites, a treated and an untreated herd were compared. In the treatment sites, cattle were treated on a regular basis using a formulation of deltamethrin 0.005% (67 to 98 cattle were treated in one of the sites and 88 to 102 in the other one). For each herd, tsetse densities were monthly monitored using 7 biconical traps set along the river and beside the cattle pen from February to December 2009. The impact of footbath treatment on tsetse populations was strong (p < 10^-3) with a reduction of 80% in total tsetse catches by the end of the 6-month footbath treatment.

Conclusions/Significance

The impact of footbath treatment as a vector control tool within an integrated strategy to manage AAT and HAT is discussed in the framework of the “One Health” concept. Like other techniques based on the treatment of cattle, this technology should be used under controlled conditions, in order to avoid the development of insecticide and acaricide resistance in tsetse and tick populations, respectively.     

Cross-Sectional Study on Attitudes among General Practitioners towards Pneumococcal Vaccination for Middle-Aged and Elderly Population in Hong Kong

Objective

To study the attitudes among general practitioners towards pneumococcal vaccination for middle-aged (50–64) and elderly population (over 65) in Hong Kong and the factors affecting their decision to advise pneumococcal vaccination for those age groups.

Design

Cross-sectional study of general practitioners in private practice in Hong Kong.

Participants

Members of Hong Kong Medical Association delivering general practice services in private sector.

Measuring Tool

Self-administered questionnaire.

Main Outcome Measures

Intention to recommend pneumococcal vaccination, barriers against pneumococcal vaccination.

Results

53.4% of the respondents would actively recommend pneumococcal vaccination to elderly patients but only 18.8% would recommend for middle-aged patients. Consultation not related to pneumococcal vaccine was the main reason for not recommending pneumococcal vaccine (43.6%). Rarity of pneumonia in their daily practice was another reason with 68.4% of respondents attending five or less patients with pneumonia each year. In multivariate analysis, factors such as respondents would get vaccination when reaching age 50 (OR_m 10.1), and attending 6 pneumonia cases or more per year (OR_m 2.28) were found to be associated with increasing likelihood for recommending vaccination to the middle-aged. While concerns of marketing a product (OR_m 0.41), consultation not related to vaccination (OR_m 0.45) and limited time (OR_m 0.38) were factors that reduced the likelihood.

Conclusion

Public policy is needed to increase the awareness of impact of pneumococcal pneumonia and the availability of preventive measures.