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.     

Expression and secretion of wheat α-amylase in Kluyveromyces lactis

The plasmid pCR1 has been constructed to express a wheat -amylase enzyme in Kluyveromyces lactis strains. The contruct is based on the vector pCXJ-kan1, which has been derived from pDK1, a native plasmid of K. lactis var. drosophilarum containing the essential regions for plasmid replication and stability. Contruct pCR1 produces an -amylase by DNA isolated from a wheat cDNA clone and is controlled by a Saccharomyces cerevisia PGK promoter. Correspondence to: C. Russell     

Les néoplasies intra-épithéliales du pénis: clinique,histologie et virologie

Analysis of 92 clinically dysplasic penile lesions revealed the presence of atypical mitoses and/or abnormalities of the basement membrane, definitive of intra-epithelial penile neoplasia, in 90% of cases. In 18.3% of patients (mean age 31 years) there was a genital human papillomavirus (HPV) infection. Histological lesions were low grade (State I) in 64% of cases, and high grade (Stages II or III) in 33% of cases, of which 4% were carcinoma in situ. HPV oncogene sequences were detected by Southern blotting in 75% and 95% of low and high grade lesions respectively, including 100% of carcinomas in situ. Patients with Stage II and III lesions were 7 to 10 years older than those with Stage I lesions, although circumcised men showed significantly fewer lesions than non-circumcised men, a difference not seen for the presence of genital HPV infection. The good correlation between morphological, histological and virological features allows screening for and early treatment of penile dysplasias.     

Nitric Oxide Synthase Activity Endogenously Modulates NMDA Receptors

Abstract: We tested the possibility that endogenous nitric oxide synthase activity regulated NMDA receptors in primary cultured striatal neurons. We monitored NMDA-induced increase in intra-cellular Ca²⁺ levels with fura-2 ratio imaging, while nitric oxide synthase activity was either increased with l -arginihe (the natural substrate of nitric oxide synthase) or inhibited using nitro- l -arginine (a specific inhibitor of nitric oxide synthase). We found that the NMDA receptor effect was slowly but strongly diminished after an l -arginine (1 m M , 15 min) treatment ( l -arginine preincubation reduced the 100 μM NMDA-induced maximal effect by 30–50%). The l -arginine blockade of NMDA receptors was long-lasting but could be partially reversed by hemoglobin (100 μM , 10 min), which binds nitric oxide. This was not observed when the neurons were treated with l -arginine together with nitro- l -arginine. Our data strongly suggest that physiological nitric oxide synthase activity could regulate NMDA receptors.     

Nitrification,denitrification, and related functional genes under elevated CO2: A meta-analysis in terrestrial ecosystems

Global change may have profound effects on soil nitrogen (N) cycling that can induce positive feedback to climate change through increased nitrous oxide (N₂O) emissions mediated by nitrification and denitrification. We conducted a meta-analysis of the effects of elevated CO₂ on nitrification and denitrification based on 879 observations from 58 publications and 46 independent elevated CO₂ experiments in terrestrial ecosystems. We investigated the effects of elevated CO₂ alone or combined with elevated temperature, increased precipitation, drought, and N addition. We assessed the response to elevated CO₂ of gross and potential nitrification, potential denitrification, and abundances of related functional genes (archaeal amoA, bacterial amoA, nirK, nirS, and nosZ). Elevated CO₂ increased potential nitrification (+28%) and the abundance of bacterial amoA functional gene (+62%) in cropland ecosystems. Elevated CO₂ increased potential denitrification when combined with N addition and higher precipitation (+116%). Elevated CO₂ also increased the abundance of nirK (+25%) and nirS (+27%) functional genes in terrestrial ecosystems and of nosZ (+32%) functional gene in cropland ecosystems. The increase in the abundance of nosZ under elevated CO₂ was larger at elevated temperature and high N (+62%). Four out of 14 two-way interactions tested between elevated CO₂ and elevated temperature, elevated CO₂ and increased precipitation, and elevated CO₂ and N addition were marginally significant and mostly synergistic. The effects of elevated CO₂ on potential nitrification and abundances of bacterial amoA and nirS functional genes increased with mean annual temperature and mean annual precipitation. Our meta-analysis thus suggests that warming and increased precipitation in large areas of the world could reinforce positive responses of nitrification and denitrification to elevated CO₂ and urges the need for more investigations in the tropical zone and on interactive effects among multiple global change factors, as we may largely underestimate the effects of global change on soil N₂O emissions.     

Filter-feeding gelatinous macrozooplankton response to climate change and implications for benthic food supply and global carbon cycle

It is often suggested that gelatinous zooplankton may benefit from anthropogenic pressures of all kinds and in particular from climate change. Large pelagic tunicates, for example, are likely to be favored over other types of macrozooplankton due to their filter-feeding mode, which gives them access to small preys thought to be less affected by climate change than larger preys. In this study, we provide model-based estimate of potential community changes in macrozooplankton composition and estimate for the first time their effects on benthic food supply and on the ocean carbon cycle under two 21st-century climate-change scenarios. Forced with output from an Earth System Model climate projections, our ocean biogeochemical model simulates a large reduction in macrozooplankton biomass in response to anthropogenic climate change, but shows that gelatinous macrozooplankton are less affected than nongelatinous macrozooplankton, with global biomass declines estimated at −2.8% and −3.5%, respectively, for every 1°C of warming. The inclusion of gelatinous macrozooplankon in our ocean biogeochemical model has a limited effect on anthropogenic carbon uptake in the 21st century, but impacts the projected decline in particulate organic matter fluxes in the deep ocean. In subtropical oligotrophic gyres, where gelatinous zooplankton dominate macrozooplankton, the decline in the amount of organic matter reaching the seafloor is reduced by a factor of 2 when gelatinous macrozooplankton are considered (−17.5% vs. −29.7% when gelatinous macrozooplankton are not considered, all for 2100 under RCP8.5). The shift to gelatinous macrozooplankton in the future ocean therefore buffers the decline in deep carbon fluxes and should be taken into account when assessing potential changes in deep carbon storage and the risks that deep ecosystems may face when confronted with a decline in their food source.     

Detection of Naegleria fowleri cysts in environmental samples by using a DNA probe

Abstract In this study we tried to detect DNA Naegleria fowleri in artificially contaminated environmental samples, with or without sediments, containing 10⁴ cysts of this pathogenic amoeba. We used two assays to extract DNA from samples: first, direct DNA extraction, which gave positive results only for water samples without sediment; second, DNA extraction after sample incubation on agar plates, which allowed us to remove amoeba growing out of the sediments, and which gave positive results for all samples, even those initially with sediments (5, 500 or 500 mg). Thus, this molecular identification appears as a powerful tool to investigate N. fowleri growth in environmental samples.     

Studies on skeleton formation in reptiles: Patterns of ossification in the skeleton of Chelydra serpentina (Reptilia, Testudines)

Patterns and sequence of ossification are described throughout the skeleton of Chelydra serpentina Linnaeus. Evidence is adduced documenting the decoupling of ossification processes from sequence and patterns of chondrification. Convergence of ontogenetic repatterning in the ossification of the axial skeleton in Chelydra and Squamata is discussed, as are problems of adaptive modification of ossification patterns. The development of a carapace may be correlated with changes of ossification patterns in the postcranial axial skeleton of turtles, but the most striking evidence for the adaptive modification of ossification sequence obtains from a comparison of the limb skeleton and its ossification in Chelydra and in sea turtles