Assessment of the immune responsiveness of mice irradiated with continuous wave or pulse-modulated 425-MHz radio frequency radiation

Groups of female BALB/C mice were irradiated with 425-MHz radio frequency (RF) radiation either continuous wave (CW) or pulse modulated (PM, 1-ms pulse width, 250 pulses/s). Mice were irradiated in a rectangular strip-transmission line at average forward powers of 78, 17.7, or 5 W for CW and 17.7, 5, or 1.25 W for PM. The mean specific absorption rate, as measured using twin-well calorimetry was 7.7 W/kg for a forward power of 70 W. No differences in the mitogen-stimulated response of lymphocytes or in the primary antibody response to sheep erythrocytes or polyvinylpyrrolidone were observed between irradiated and sham-irradiated mice, nor between mice exposed to either CW or PM 425-MHz RF radiation.     

Effects of climate change on productivity of cereals and legumes; model evaluation of observed year-to-year variability of the CO2 response

The effect of elevated [CO₂] on the productivity of spring wheat, winter wheat and faba bean was studied in experiments in climatized crop enclosures in the Wageningen Rhizolab in 1991–93. Simulation models for crop growth were used to explore possible causes for the observed differences in the CO₂ response. Measurements of the canopy gas exchange (CO₂ and water vapour) were made continuously from emergence until harvest. At an external [CO₂] of 700 μmol mol^?1 Maximum Canopy CO₂ Exchange Rate (CCERmax) at canopy closure was stimulated by 51% for spring wheat and by 71% for faba bean. At the end of the growing season, above ground biomass increase at 700 μmol mol^?1 was 58% (faba bean), 35% (spring wheat) and 19% (winter wheat) and the harvest index did not change. For model exploration, weather data sets for the period 1975-88 and 1991–93 were used, assuming adequate water supply and [CO₂] at 350 and 700 μmol mol^?1. For spring wheat the simulated responses (35–50%) were at the upper end of the experimental results. In agreement with experiments, simulations showed smaller responses for winter wheat and larger responses for faba bean. Further model explorations showed that this differential effect in the CO₂ response may not be primarily due to fundamental physiological differences between the crops, but may be at least partly due to differences in the daily air temperatures during comparable stages of growth of these crops. Simulations also showed that variations between years in CO₂ response can be largely explained by differences in weather conditions (especially temperature) between growing seasons.     

Contrasting reactivity of thioglucoside and selenoglucoside donors towards promoters: implications for glycosylation stereocontrol

The stereochemical outcome of glycosylation reactions with model thioglycosides and selenoglycosides proved to be dependent on the source of promoter iodonium ion, with iodine giving different results to N-iodosuccinimide (NIS) alone or N-iodosuccinimide/trimethylsilyltrifluoromethanesulfonate (NIS/TMSOTf). In contrast to armed thioglycosides, which anomerise, and disarmed thioglycosides, which do not react, both armed and disarmed selenoglycosides give rise to the corresponding glycosyl iodides when reacted with iodine. Further, whilst the single electron transfer agent DDQ alone is an ineffective promoter, in combination with iodine it produces better acetonitrile-assisted beta-stereoselectivity with both thioglycosides and selenoglycosides than does tris(4-bromophenyl)aminium hexachloroantimonate (BAHA).     

Stability of globular proteins in H2O and D2O

In several experimental techniques D2O rather then H2O is often used as a solvent for proteins. Concerning the influence of the solvent on the stability of the proteins, contradicting results have been reported in literature. In this paper the influence of H2O-D2O solvent substitution on the stability of globular protein structure is determined in a systematic way. The differential scanning calorimetry technique is applied to allow for a thermodynamic analysis of two types of globular proteins: hen's egg lysozyme (LSZ) with relatively strong internal cohesion ("hard" globular protein) and bovine serum albumin (BSA), which is known for its conformational adaptability ("soft" globular protein). Both proteins tend to be more stable in D2O compared to H2O. We explain the increase of protein stability in D2O by the observation that D2O is a poorer solvent for nonpolar amino acids than H2O, implying that the hydrophobic effect is larger in D2O. In case of BSA the transitions between different isomeric forms, at low pH values the Nm and F forms, and at higher pH values Nm and B, were observed by the presence of a supplementary peak in the DSC thermogram. It appears that the pH-range for which the Nm form is the preferred one is wider in D2O than in H2O.     

Deep ploughing increases agricultural soil organic matter stocks

Subsoils play an important role within the global C cycle, since they have high soil organic carbon (SOC) storage capacity due to generally low SOC concentrations. However, measures for enhancing SOC storage commonly focus on topsoils. This study assessed the long‐term storage and stability of SOC in topsoils buried in arable subsoils by deep ploughing, a globally applied method for breaking up hard pans and improving soil structure to optimize crop growing conditions. One effect of deep ploughing is translocation of SOC formed near the surface into the subsoil, with concomitant mixing of SOC‐poor subsoil material into the ‘new’ topsoil. Deep‐ploughed croplands represent unique long‐term in situ incubations of SOC‐rich material in subsoils. In this study, we sampled five loamy and five sandy soils that were ploughed to 55–90 cm depth 35–50 years ago. Adjacent, similarly managed but conventionally ploughed subplots were sampled as reference. The deep‐ploughed soils contained on average 42 ± 13% more SOC than the reference subplots. On average, 45 years after deep ploughing, the ‘new’ topsoil still contained 15% less SOC than the reference topsoil, indicating long‐term SOC accumulation potential in the topsoil. In vitro incubation experiments on the buried sandy soils revealed 63 ± 6% lower potential SOC mineralisation rates and also 67 ± 2% lower SOC mineralisation per unit SOC in the buried topsoils than in the reference topsoils. Wider C/N ratio in the buried sandy topsoils than in the reference topsoils indicates that deep ploughing preserved SOC. The SOC mineralisation per unit SOC in the buried loamy topsoils was not significantly different from that in the reference topsoils. However, 56 ± 4% of the initial SOC was preserved in the buried topsoils. It can be concluded that deep ploughing contributes to SOC sequestration by enlarging the storage space for SOC‐rich material.     

Solid-phase synthesis of cyclic RGD-furanoid sugar amino acid peptides as integrin inhibitors

The solid-phase synthesis of cyclic RGD peptides containing either one or two furanoid sugar amino acids (SAAs) is reported. Using a cyclization-cleavage approach five peptides were successfully assembled and consecutively tested on their ability to bind to the integrin receptors alpha(v)beta(3) and alpha(IIb)beta(3). The cyclic tetrapeptide c[RGD-SAA] (1) showed the most promising activity in an inhibition assay with an IC(50) of 1.49 microM for the alpha(v)beta(3) receptor and 384 nM for the alpha(IIb)beta(3) receptor.     

Seasonal changes in the response of winter wheat to elevated atmospheric CO2 concentration grown in Open-Top Chambers and field tracking enclosures

Winter wheat was grown at ambient and elevated (ambient plus 350 μL L^–1) CO₂ concentrations in open top chambers and in field-tracking sun-lit climatized enclosures (elevated is 718 μL L^–1). There was no significant effect of CO₂ concentration on sheath, leaf and root biomass and leaf area in the early spring (January to April). 24-h canopy CO₂ exchange rate (CCER) was not significantly affected either. However, elevated CO₂ concentration increased CCER at midday, decreased evapotranspiration rate and increased instantaneous water-use-efficiency during early spring. Leaf, sheath and root nitrogen concentration per unit dry weight decreased and nonstructural carbohydrate concentration increased under elevated CO₂, and N-uptake per unit ground area decreased significantly (– 22%) towards the end of this period. These results contrast with results from the final harvest, when grain yield and biomass were increased by 19% under elevated CO₂. N concentration per dry weight was reduced by 5%, but N-uptake per unit ground area was significantly higher (+ 11%) for the elevated CO₂ treatment. 24-h and midday-CCER increased significantly more in late spring (period of 21 April to 30 May) (respectively by + 40% and 53%) than in the early spring (respectively 5% and 19%) in response to elevated CO₂. Midday evapotranspiration rate was reduced less by elevated CO₂ in the late spring (– 13%) than in early spring (– 21%). The CO₂ response of midday and 24-h CCER decreased again (+ 27% and + 23% resp.) towards the end of the growing season. We conclude that the low response to CO₂ concentration during the early spring was associated with a growth-restriction, caused by low temperature and irradiance levels. The reduction of nitrogen concentration, the increase of nonstructural carbohydrate, and the lower evapotranspiration indicated that CO₂ did have an effect towards the end of early spring, but not on biomass accumulation. Regression analysis showed that both irradiance and temperature affected the response to CO₂.     

Evolution of the relaxin-like peptide family

Background  

The relaxin-like peptide family belongs in the insulin superfamily and consists of 7 peptides of high structural but low sequence similarity; relaxin-1, 2 and 3, and the insulin-like (INSL) peptides, INSL3, INSL4, INSL5 and INSL6. The functions of relaxin-3, INSL4, INSL5, INSL6 remain uncharacterised. The evolution of this family has been contentious; high sequence variability is seen between closely related species, while distantly related species show high similarity; an invertebrate relaxin sequence has been reported, while a relaxin gene has not been found in the avian and ruminant lineages.