Minos as a genetic and genomic tool in Drosophila melanogaster

Much of the information about the function of D. melanogaster genes has come from P-element mutagenesis. The major drawback of the P element, however, is its strong bias for insertion into some genes (hotspots) and against insertion into others (coldspots). Within genes, 5′-UTRs are preferential targets. For the successful completion of the Drosophila Genome Disruption Project, the use of transposon vectors other than P will be necessary. We examined here the suitability of the Minos element from Drosophila hydei as a tool for Drosophila genomics. Previous work has shown that Minos, a member of the Tc1/mariner family of transposable elements, is active in diverse organisms and cultured cells; it produces stable integrants in the germ line of several insect species, in the mouse, and in human cells. We generated and analyzed 96 Minos integrations into the Drosophila genome and devised an efficient “jump-starting” scheme for production of single insertions. The ratio of insertions into genes vs. intergenic DNA is consistent with a random distribution. Within genes, there is a statistically significant preference for insertion into introns rather than into exons. About 30% of all insertions were in introns and ~55% of insertions were into or next to genes that have so far not been hit by the P element. The insertion sites exhibit, in contrast to other transposons, little sequence requirement beyond the TA dinucleotide insertion target. We further demonstrate that induced remobilization of Minos insertions can delete nearby sequences. Our results suggest that Minos is a useful tool complementing the P element for insertional mutagenesis and genomic analysis in Drosophila.     

Estimating lagoonal biodiversity in Greece: comparison of rapid assessment techniques

An attempt is made to compare the results of different rapid biodiversity assessment techniques at the pan-Mediterranean, sectorial and local levels. A uniform multivariate pattern exists at the pan-Mediterranean and national (sectorial) levels: lagoons can be different when they host only a few species, but as species numbers increase, lagoons become homogenous in composition. Multivariate techniques cannot distinguish anthropogenically-impacted lagoons from those, which are naturally disturbed. In the pan-Mediterranean context it is the higher taxonomic levels, but in the national and local context it is the most abundant macrobenthic groups (polychaetes, molluscs and crustaceans) and meiobenthos which provide patterns closest to that derived from the species level. Taxonomic distinctness indices applied to polychaete and mollusc inventories provide meaningful results at most levels and scales of observation. These indices seem to be robust enough to discriminate anthropogenically impacted from naturally disturbed lagoons.     

Hamstring antagonist moment estimation using clinically applicable models: Muscle dependency and synergy effects.

The purpose of this study was to examine whether prediction of antagonist moment (M(flx)) of the hamstrings using clinically applicable models depends on the muscles examined. Nine healthy males performed maximal isometric knee extension and flexion contractions at 0 degrees , 45 degrees and 90 degrees angles. Calibration knee flexion efforts were also performed at different levels of intensity. The resulting electromyographic (EMG) - moment curves were fitted using polynomial equations which were then used to estimate M(flx) from the antagonist EMG. Analysis of variance designs showed that the M(flx) predicted using the biceps femoris EMG was not significantly different compared with those predicted using the semitendinosus EMG data (p>0.05). Further, prediction of M(flx) using the EMG of both muscles or a combination of EMGs and architectural properties reduced estimation error but did not provide significantly different predicted values compared with the simpler single-muscle EMG - moment models (p<0.05). It appears that M(flx) prediction using the present EMG - moment model is not muscle specific. Prediction using models which combine EMG data and anatomic parameters of the hamstring muscle components yielded more accurate estimates and therefore their use to examine co-contraction levels is recommended.     

Leptophytum flavescens comb. nov. (Corallinales,Rhodophyta), an Arctic endemic from the sublittoral of NW Spitsbergen,North Norway,and western Novaya Zemlya,with epitypification of L. laeve

Type material of Lithothamnion flavescens Kjellman, originally described from Karlsøy (Troms) and Karmakul Bay (Novaya Zemlya), is re-examined and a lectotype is selected. Type specimens and other collections from NW Spitsbergen and North Norway possess distinctive characters of the genus Leptophytum, including the development of flattened epithallial cells, short subepithallial cells, and simple spermatangial structures. Leptophytum flavescens (Kjellman) comb. nov. resembles the generitype Leptophytum laeve, differing in having: (1) a thicker perithallium, to 900?µm (vs. 350?µm in L. laeve), that embeds older conceptacles, and (2) non-differentiated (in size or shape) pore cells of multiporate roofs. An epitype for L. laeve is also selected, which consolidates the status of this species and the genus, in agreement with the current literature and all publications prior to 1996.     

Early midcell localization of Escherichia coli PBP4 supports the function of peptidoglycan amidases

Insertion of new material into the Escherichia coli peptidoglycan (PG) sacculus between the cytoplasmic membrane and the outer membrane requires a well-organized balance between synthetic and hydrolytic activities to maintain cell shape and avoid lysis. Since most bacteria carry multiple enzymes carrying the same type of PG hydrolytic activity, we know little about the specific function of given enzymes. Here we show that the DD-carboxy/endopeptidase PBP4 localizes in a PBP1A/LpoA and FtsEX dependent fashion at midcell during septal PG synthesis. Midcell localization of PBP4 requires its non-catalytic domain 3 of unknown function, but not the activity of PBP4 or FtsE. Microscale thermophoresis with isolated proteins shows that PBP4 interacts with NlpI and the FtsEX-interacting protein EnvC, an activator of amidases AmiA and AmiB, which are needed to generate denuded glycan strands to recruit the initiator of septal PG synthesis, FtsN. The domain 3 of PBP4 is needed for the interaction with NlpI and EnvC, but not PBP1A or LpoA. In vivo crosslinking experiments confirm the interaction of PBP4 with PBP1A and LpoA. We propose that the interaction of PBP4 with EnvC, whilst not absolutely necessary for mid-cell recruitment of either protein, coordinates the activities of PBP4 and the amidases, which affects the formation of denuded glycan strands that attract FtsN. Consistent with this model, we found that the divisome assembly at midcell was premature in cells lacking PBP4, illustrating how the complexity of interactions affect the timing of cell division initiation.     

Type IV secretion system core component VirB8 from Brucella binds to the globular domain of VirB5 and to a periplasmic domain of VirB6

Type IV secretion systems are macromolecular assemblies in the cell envelopes of bacteria that function in macromolecular translocation. Structural biology approaches have provided insights into the interaction of core complex components, but information about proteins that undergo transient interactions with membrane components has not been forthcoming. We have pursued an unbiased approach using peptide arrays and phage display to identify interaction partners and interaction domains of type IV secretion system assembly factor VirB8. These approaches identified the globular domain from the VirB5 protein to interact with VirB8. This interaction was confirmed in cross-linking, pull-down, and fluorescence resonance energy transfer (FRET)-based interaction assays. In addition, using phage display analysis, we identified different regions of VirB6 as potential interaction partners of VirB8. Using a FRET-based interaction assay, we provide the first direct experimental evidence of the interaction of a VirB6 periplasmic domain with VirB8. These results will allow us to conduct directed structural biological work and structure-function analyses aimed at defining the molecular details and biological significance of these interactions with VirB8 in the future.     

Time Trends of Helicobacter pylori Resistance to Antibiotics in Children Living in Vienna,Austria

Background: Increase of antibiotic resistance is a worldwide problem. Within the 4 years before the turn of the millennium Helicobacter pylori strains isolated in children living in Vienna, Austria, showed a primary clarithromycin and metronidazole resistance of 20% and 16%, respectively. The aim of this retrospective follow‐up survey was to assess the further development and current antimicrobial resistance status. Methods: Children having undergone upper endoscopy between March 2002 and March 2008 at the same two co‐operating pediatric gastroenterology units which had also been collaborating on the prior assessment were included. H. pylori infection was diagnosed by rapid urease test, histology, and culture. If the latter was positive, susceptibility testing to amoxicillin, clarithromycin and metronidazole by E‐test followed. From March 2004 onwards, susceptibility to levofloxacin, tetracycline and rifampin was additionally assessed. Results: Out of 897 children, 153 had a proven infection with H. pylori and no history of prior eradication treatment. Their median age was 11.5 years (range 0.5–20.9 years). Primary resistance to clarithromycin and metronidazole were 34% and 22.9%, respectively; dual resistance was found in 9.8% of the strains; 0.9% was resistant to tetracycline and rifampin, respectively. No case of amoxicillin resistance was detected. The only independent risk factor for clarithromycin resistance turned out to be the origin of a child from Austrian parents. Conclusions: In the last decade, the rate of primary resistance of H. pylori to clarithromycin continued to rise. No significant change was found regarding primary resistance to metronidazole or dual resistance to metronidazole and clarithromycin, respectively.     

The low-density lipoprotein (LDL)-associated PAF-acetylhydrolase activity and the extent of LDL oxidation are important determinants of the autoantibody titers against oxidized LDL in patients with coronary artery disease

The oxidation of low-density lipoprotein (LDL) induces immunogenic epitopes, many of which are due to oxidatively modified phospholipids (oxPL). Lysophosphatidylcholine (lyso-PC) which is generated during LDL oxidation through the hydrolysis of oxPL by LDL-associated PAF-acetylhydrolase (PAF-AH) is also immunogenic. We investigated whether the LDL-associated PAF-AH and the extent of LDL oxidation influence the autoantibody titers against oxidized LDL (oxLDL) in patients with stable angina as well as in apparently healthy volunteers. Three types of copper-oxidized LDL, were prepared at the end of the lag, propagation or decomposition phase (oxLDL(L), oxLDL(P) and oxLDL(D), respectively). Similar types of oxidized LDL were prepared after previous inactivation of endogenous PAF-AH [oxLDL(-)]. All these types of oxLDL as well as malondialdehyde-modified LDL (MDA-LDL) were used as antigens. Antibody titers against the above antigens were measured with an ELISA method in the serum of 65 patients with stable angina and 47 apparently healthy volunteers. Both groups exhibited higher autoantibody titers against each type of oxLDL(-) compared to the respective type of oxLDL (P<0.00001). In both groups autoantibody titers were higher when the oxLDL(P) and oxLDL(D) or oxLDL(-)(P) and oxLDL(-)(D) were used as antigens compared to oxLDL(L) (P<0.04) or to oxLDL(-)(L), respectively (P<0.0001 for all comparisons). Patients had significantly higher titers against all types of oxLDL (enriched in lyso-PC) and oxLDL(-) (enriched in intact oxPL) compared to controls. Autoantibody titers against MDA-LDL did not differ between patients and controls. Multivariate logistic regression analysis showed that among the autoantibody titers measured only those towards oxLDL(P) are associated with a significantly higher risk for coronary artery disease. LDL-associated PAF-AH activity may play an important role in decreasing the overall immunogenicity of oxLDL, whereas the extent of LDL oxidation seems to modulate the epitopes formed on oxLDL. Lyso-PC, a major component of oxLDL(P), could be mainly responsible for the elevated autoantibody titers against oxLDL in patients with stable angina.