The wing base of the palaeodictyopteran genus Dunbaria Tillyard: Where are we now?

The structure of insect wing articulation is considered as reliable source of high level characters for phylogenetic analyses. However, the correct identification of homologous structures among the main groups of Pterygota is a hotly debated issue. Therefore, the reconstruction of the wing bases in Paleozoic extinct relatives is of great interest, but at the same time it should be treated with extreme caution due to distortions caused by taphonomic effects. The present study is focused on the wing base in Dunbaria (Spilapteridae). The articulation in Dunbaria quinquefasciata is mainly formed by a prominent upright axillary plate while the humeral plate is markedly reduced. Due to unique preservation of surface relief of the axillary plate, its composition shows a detailed pattern of three fused axillary sclerites and presumable position of the sclerite 3Ax. The obtained structures were compared among Spilapteridae and to other palaeodictyopterans Ostrava nigra (Homoiopteridae) and Namuroningxia elegans (Namuroningxiidae). The comparative study uncovered two patterns of 3Ax in Dunbaria and Namuroningxia, which correspond to their different suprafamilial classification. In contrast to previous studies these new results reveal the homologous structural elements in the wing base between Paleozoic Palaeodictyoptera and their extant relatives of Ephemeroptera, Odonata and Neoptera.     

New fossil arthropods (Notostraca and Insecta: Syntonopterida) in the Continental Middle Permian of Provence (Bas-Argens Basin,France)

Apart frequent and relatively common ichnites, only a few body fossils (Ostracoda) have been mentioned in the Red Continental Permian formations of Provence till these last years. During 2006 and 2007 field researches, new arthropods have been discovered in the Pradineaux Formation of the Bas-Argens. They are Triopsidae (Crustacea, Notostraca) and an insect wing (Syntonopteridae) corresponding to a new genus and species Gallolithoneura butchlii gen. et sp. n. This latter is the first insect record in the Permian of Provence and the youngest one of this enigmatic Carboniferous paleopteran family. As in the other French Permian basins (Lodève, Saint-Affrique), these discoveries demonstrate that the Permian Provençal paleofauna was rich and diverse. For the Upper part of the Pradineaux Formation, Capitanian (Upper Guadalupian) in age, the Triopsidae mean the presence of periodical ponds settled in a playa environment evolving under a xerophytic climate. Gallolithoneura butchlii suggests also the presence of aquatic habitats.     

Monomeric solution structure of the helicase-binding domain of Escherichia coli DnaG primase

DnaG is the primase that lays down RNA primers on single-stranded DNA during bacterial DNA replication. The solution structure of the DnaB-helicase-binding C-terminal domain of Escherichia coli DnaG was determined by NMR spectroscopy at near-neutral pH. The structure is a rare fold that, besides occurring in DnaG C-terminal domains, has been described only for the N-terminal domain of DnaB. The C-terminal helix hairpin present in the DnaG C-terminal domain, however, is either less stable or absent in DnaB, as evidenced by high mobility of the C-terminal 35 residues in a construct comprising residues 1-171. The present structure identifies the previous crystal structure of the E. coli DnaG C-terminal domain as a domain-swapped dimer. It is also significantly different from the NMR structure reported for the corresponding domain of DnaG from the thermophile Bacillus stearothermophilus. NMR experiments showed that the DnaG C-terminal domain does not bind to residues 1-171 of the E. coli DnaB helicase with significant affinity.     

CD-3-mediated activation of MAP-2 kinase can be modified by ligation of the CD4 receptor. Evidence for tyrosine phosphorylation during activation of this kinase

The CD4R has been shown to exert variable effects on T cell activation responses. Depending on the manner of ligation, the CD4R has been demonstrated to have positive as well as negative effects on the generation of [Ca2+]i flux by the CD3R. Coaggregation of CD3 with CD4 enhanced Ca2+ flux while their independent ligation and aggregation diminished this response. To further elucidate these paradoxical CD4 effects, we studied induction of a microtubule-associated protein 2 kinase (MAP-2K) activity during ligation of the CD3R. Lymphoid MAP-2K activation by CD3 is an evanescent event that is dependent on phosphorylation of 43-kDa MAP-2K via a pathway that involves protein kinase C. Coaggregation of CD4 and CD3 with cross-linking antibodies and avidin enhanced the CD3-mediated MAP-2K response almost twofold. In contrast, independent ligation and cross-linking of CD4 reduced the CD3-induced MAP-2K response by approximately 50%. An important requirement for this inhibitory effect was that CD4 be ligated before stimulation with anti-CD3. The negative effect of anti-CD4 mAb was specific as other mAb failed to simulate this event. The PMA-induced MAP-2K response was not inhibited by anti-CD4. Intact 32P-labeled Jurkat and normal human T cells demonstrated the appearance of a single 43-kDa tyrosine phosphoprotein during stimulation with PMA and anti-CD3. When these crude cellular extracts were extensively fractionated across DEAE- and hydrophobic columns, MAP-2K was resolved into two peaks of activity, each containing a single tyrosine phosphoprotein around 43 kDa. In addition to tyrosine-specific labeling, mitogenic stimulation of normal human T cells also induced threonine-specific labeling of MAP-2K. These results imply that activation of lymphoid MAP-2K is a dual process requiring at least two independent kinases for optimal activity. Inasmuch as CD3 activates protein kinase C and CD4 is associated with a tyrosine kinase, pp56lck, we suggest that their coaggregation may create the conditions whereby MAP-2K may be activated by dual phosphorylation. Independent aggregation of these receptors may lead to physical separation and breakdown of this interactive mechanism.     

Discovery of the oldest known Pterygota in the Lower Carboniferous of the Upper Silesian Basin in the Czech Republic (Insecta: Archaeorthoptera)

The earliest pterygote (winged insect), dated from the Lower Carboniferous (Namurian A/E1, circa 324 millions years ago) is described from the Upper Silesian Basin in the Czech Republic. On the basis of its wing venation, it is attributed to the Archaeorthoptera Béthoux and Nel, 2002, crown group of the “Orthoptera”. Besides Apterygota (Collembola and Archaeognatha) known from the Lower Devonian, extremely rare pterygote insects are known from Lower Carboniferous deposits when they first appeared. The present discovery supports the hypothesis of the presence of the ancestor lineage of the orthopteroid in the Lower Carboniferous ecosystems.     

Rivers in peril inside and outside protected areas: a systematic approach to conservation assessment of river ecosystems

This paper establishes a framework within which a rapid and pragmatic assessment of river ecosystems can be undertaken at a broad, subcontinental scale, highlighting some implications for achieving conservation of river biodiversity in water‐limited countries. The status of river ecosystems associated with main rivers in South Africa was assessed based on the extent to which each ecosystem had been altered from its natural condition. This requires consistent data on river integrity for the entire country, which was only available for main rivers; tributaries were thus excluded from the analyses. The state of main river ecosystems in South Africa is dire: 84% of the ecosystems are threatened, with a disturbing 54% critically endangered, 18% endangered, and 12% vulnerable. Protection levels were measured as the proportion of conservation target achieved within protected areas, where the conservation target was set as 20% of the total length of each river ecosystem. Sixteen of the 112 main river ecosystems are moderately to well represented within protected areas; the majority of the ecosystems have very low levels of representation, or are not represented at all within protected areas. Only 50% of rivers within protected areas are intact, but this is a higher proportion compared to rivers outside (28%), providing some of the first quantitative data on the positive role protected areas can play in conserving river ecosystems. This is also the first assessment of river ecosystems in South Africa to apply a similar approach to parallel assessments of terrestrial, marine, and estuarine ecosystems, and it revealed that main river ecosystems are in a critical state, far worse than terrestrial ecosystems. Ecosystem status is likely to differ with the inclusion of tributaries, since options may well exist for conserving critically endangered ecosystems in intact tributaries, which are generally less regulated than main rivers. This study highlights the importance of healthy tributaries for achieving river conservation targets, and the need for managing main rivers as conduits across the landscape to support ecological processes that depend on connectivity. We also highlight the need for a paradigm shift in the way protected areas are designated, as well as the need for integrated river basin management plans to include explicit conservation visions, targets, and strategies to ensure the conservation of freshwater ecosystems and the services they provide.     

Air-pollutant chemicals and oxidized lipids exhibit genome-wide synergistic effects on endothelial cells

Background  

Ambient air pollution is associated with increased cardiovascular morbidity and mortality. We have found that exposure to ambient ultrafine particulate matter, highly enriched in redox cycling organic chemicals, promotes atherosclerosis in mice. We hypothesize that these pro-oxidative chemicals could synergize with oxidized lipid components generated in low-density lipoprotein particles to enhance vascular inflammation and atherosclerosis.     

Engineering [Ln(DPA)3] 3- binding sites in proteins: a widely applicable method for tagging proteins with lanthanide ions

Paramagnetic relaxation enhancements from unpaired electrons observed in nuclear magnetic resonance (NMR) spectra present powerful long-range distance restraints. The most frequently used paramagnetic tags, however, are tethered to the protein via disulfide bonds, requiring proteins with single cysteine residues for covalent attachment. Here we present a straightforward strategy to tag proteins site-specifically with paramagnetic lanthanides without a tether and independent of cysteine residues. It relies on preferential binding of the complex between three dipicolinic acid molecules (DPA) and a lanthanide ion (Ln³⁺), [Ln(DPA)₃]³⁻, to a pair of positively charged amino acids whose charges are not compensated by negatively charged residues nearby. This situation rarely occurs in wild-type proteins, allowing the creation of specific binding sites simply by introduction of positively charged residues that are positioned far from glutamate or aspartate residues. The concept is demonstrated with the hnRNPLL RRM1 domain. In addition, we show that histidine- and arginine-tags present binding sites for [Ln(DPA)₃]³⁻.     

Exposure to non-steroidal anti-inflammatory drugs during pregnancy and the risk of selected birth defects: a prospective cohort study

Background

Since use of non-steroidal anti-inflammatory drugs (NSAIDs) during pregnancy is common, small increases in the risk of birth defects may have significant implications for public health. Results of human studies on the teratogenic risks of NSAIDs are inconsistent. Therefore, we evaluated the risk of selected birth defects after prenatal exposure to prescribed and over-the-counter NSAIDs.

Methods and Findings

We used data on 69,929 women enrolled in the Norwegian Mother and Child Cohort Study between 1999 and 2006. Data on NSAID exposure were available from a self-administered questionnaire completed around gestational week 17. Information on pregnancy outcome was obtained from the Medical Birth Registry of Norway. Only birth defects suspected to be associated with NSAID exposure based upon proposed teratogenic mechanisms and previous studies were included in the multivariable logistic regression analyses. A total of 3,023 women used NSAIDs in gestational weeks 0–12 and 64,074 women did not report NSAID use in early pregnancy. No associations were observed between overall exposure to NSAIDs during pregnancy and the selected birth defects separately or as a group (adjusted odds ratio 0.7, 95% confidence interval 0.4–1.1). Associations between maternal use of specific types of NSAIDs and the selected birth defects were not found either, although an increased risk was seen for septal defects and exposure to multiple NSAIDs based on small numbers (2 exposed cases; crude odds ratio 3.9, 95% confidence interval 0.9–15.7).

Conclusions

Exposure to NSAIDs during the first 12 weeks of gestation does not seem to be associated with an increased risk of the selected birth defects. However, due to the small numbers of NSAID-exposed infants for the individual birth defect categories, increases in the risks of specific birth defects could not be excluded.