Large-scale copy number polymorphism in the human genome

The extent to which large duplications and deletions contribute to human genetic variation and diversity is unknown. Here, we show that large-scale copy number polymorphisms (CNPs) (about 100 kilobases and greater) contribute substantially to genomic variation between normal humans. Representational oligonucleotide microarray analysis of 20 individuals revealed a total of 221 copy number differences representing 76 unique CNPs. On average, individuals differed by 11 CNPs, and the average length of a CNP interval was 465 kilobases. We observed copy number variation of 70 different genes within CNP intervals, including genes involved in neurological function, regulation of cell growth, regulation of metabolism, and several genes known to be associated with disease.     

Parent volatiles in comet 9P/Tempel 1: before and after impact

We quantified eight parent volatiles (H2O, C2H6, HCN, CO, CH3OH, H2CO, C2H2, and CH4) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy in the wavelength range 2.8 to 5.0 micrometers. The abundance ratio for ethane was significantly higher after impact, whereas those for methanol and hydrogen cyanide were unchanged. The abundance ratios in the ejecta are similar to those for most Oort cloud comets, but methanol and acetylene are lower in Tempel 1 by a factor of about 2. These results suggest that the volatile ices in Tempel 1 and in most Oort cloud comets originated in a common region of the protoplanetary disk.     

Microbial ethylene production and inhibition of methanotrophic activity in a deciduous forest soil

Production of C₂H₄, but not of CH₄, was observed in anoxically incubated soil samples (cambisol on loamy sand) from a deciduous forest. Ethylene production was prevented by autoclaving, indicating its microbial origin. Ethylene production gradually decreased from 4 to 12 cm soil depth and was not affected by moisture or addition of methionine, a possible precursor of C₂H₄. Oxidation of atmospheric CH₄ in soil samples was inhibited by C₂H₄. Ethylene concentrations of 3, 6 and 10 μl l⁻¹ decreased CH₄ uptake by 21, 63 and 98%, respectively. Methionine and methanethiol, a possible product of methionine degradation, also inhibited CH₄ oxidation. Under oxic conditions, C₂H₄ was consumed in the soil samples. Ethylene oxidation kinetics exhibited two apparent K_m values of 40 μl l⁻¹ and 12,600 μl l⁻¹ suggesting the presence of two different types of C₂H₄-oxidizing microorganisms. Methanotrophic bacteria were most probably not responsible for C₂H₄ oxidation, since the maximum of C₂H₄ oxidation activity was localized in soil layers (2-8 cm depth) above those (8-10 cm depth) of CH₄ oxidation activity. Our observations suggest that C₂H₄ production in the upper soil layers inhibits CH₄ oxidation, thus being one reason for the localization of methanotrophic activity in deeper soil layers.     

Influence of oxygen on production and consumption of nitric oxide in soil

Summary NO and N₂O release rates were measured in an acidic forest soil (pH 4.0) and a slightly alkaline agricultural soil (pH 7.8), which were incubated at different O₂ concentrations (<0.01 – 20% O₂) and at different NO concentrations (40 – 1000 ppbv NO). The system allowed the determination of simultaneously operating NO production rates and NO uptake rate constants, and the calculation of a NO compensation concentration. Both NO production and NO consumption decreased with increasing O₂. NO consumption decreased to a smaller extent than NO production, so that the NO compensation concentrations also decreased. However, the NO compensation concentrations were not low enough for the soils to become a net sink for atmospheric NO. The release of N₂O increased relative to NO release when the gases were allowed to accumulate instead of being flushed out. The forest soil contained only denitrifying, but not nitrifying bacteria, whereas the agricultural soil contained both. Nevertheless, NO release rates were less sensitive to O₂ in the forest soil compared to the agricultural soil.     

Suitability of satellite remote sensing data for yield estimation in northeast Germany

Precision Agriculture - Information provided by satellite data is becoming increasingly important in the field of agriculture. Estimating biomass, nitrogen content or crop yield can improve farm...     

Die Aminosäuren-Zusammensetzung des sedimentierbaren Plasma-Proteins verschiedener Segmente der Keimlingswurzel vonPisum sativum

Zusammenfassung Wurzeln etiolierter Erbsenkeimlinge wurden im Phywe-Homogenisator zerkleinert, die Zellwandreste wurden durch Filtration entfernt und die Plasmapartikel durch Zentrifugieren bei 20 000 g abgetrennt. In den auf diese Weise sedimentierten Plasmaproteinen wurde durch etwas modifizierte quantitative Papierchromatographie nach McFarren die Aminosäurezusammensetzung untersucht. Dazu wurden die Proteinhydrolysate auf Schleicher & Schüll-Papier 2043b mit sechs verschiedenen Laufmitteln getrennt (Phenol pH 1; Phenol pH 12; Methyläthylketon-Pyridin-Puffer pH 6,2 = 5:1:1; t-Butanol pH 8,5; n-Butanol-Eisessig-Wasser = 4:1:5; Kollidin pH 9). In dieser Weise wurden 15, jeweils 1 mm lange Wurzelsegmente, von der Spitze an gerechnet, getrennt analysiert. Im Partikelprotein keines dieser Segmente konnte -Aminobuttersäure oder Hydroxyprolin nachgewiesen werden. Die Proteine aus den verschiedenen Wurzelabschnitten ergaben eine sehr ähnliche Aminosäurezusammensetzung. Geringe Unterschiede zeigten die Spitzensegmente (0–4 mm) gegenüber den älteren Wurzelabschnitten. Im Protein der jüngsten Segmente fanden sich etwas mehr Aminosäuren der Aspartat- und Glutamatfamilie sowie Arginin und Tryptophan, welche in den älteren Wurzelteilen in geringerer Menge vorkommen. Diese enthielten jedoch mehr aromatische und langkettige Aminosäuren als die Spitzensegmente. Die Aminosäurenzusammensetzung der sedimentierbaren Partikelproteine der Erbsenwurzel wird mit entsprechenden Angaben in der Literatur über andere Leguminosenproteine, besonders aus Erbsen, verglichen.

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Summary Roots of etiolized pea seedlings were homogenized by Phywe-blendor, cell debris removed by filtration, and plasmatic particles collected by centrifuging at 20 000 g. From cell particles isolated in such way the amino acid composition in cytoplasmic proteins was analyzed by quantitative paper chromatography by the somewhat modified McFarren method. Amino acids of hydrolized proteins were separated on Schleicher & Schuell paper 2043b by 6 different solvents (phenol pH 1; phenol pH 12; methylethylketone-pyridine-buffer pH 6,2 = 5:1:1; t-butanol pH 8,5; n-butanol-acetic acid-water = 4:1:5; collidine pH 9). In such way proteins of fifteen segments, each of 1 mm length, were investigated, beginning with the top. In all segments analyzed neither -aminobutyric acid nor hydroxyproline were found in the proteins of pea root particles. Amino acid composition in proteins of different root segments proved to be similar. Slight differences were found between top segments (1–4) and the older ones. Proteins of the youngest segments contain more amino acids of the aspartate and glutamate family as well as arginine and tryptophane than the older segments. These, however, contained more aromatic and long chain amino acids than the top segments. The amino acid composition in proteins of pea roots is compared with data on other leguminous proteins, in particular of peas, described in literature.

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Kinetics and electron transport of soil hydrogenases catalyzing the oxidation of atmospheric hydrogen

The soil hydrogenases of chernozem and eolian sand were different with respect to their kinetic properties. Increase of soil moisture above optimum moisture content or prior incubation of the soils under very high H₂-mixing ratios (i.e. 1%) resulted in a decrease of V_max or in an increase of the K_m of the H₂ oxidation reaction. Under anaerobic conditions, the K_m for H₂ was higher and V_max was lower than under aerobic conditions. The anaerobic H₂-oxidation activity of both soils was stimulated by the addition of artificial electron acceptors with redox potentials of at least 80 mV. Ferricyanide as the most efficient stimulator did not function as a final electron acceptor for anaerobic H₂-oxidation, but acted as a catalyst by bypassing a rate-limiting electron transport step. In eolian sand, the aerobic as well as the anaerobic activity for atmospheric H₂ oxidation decreased upon exposure to very high H₂-mixing ratios (i.e. 1%). A similar effect was observed after incubation with ferricyanide which enabled the inflow of excess electrons from soil reductants or added NADH into the electron transport system of the soil hydrogenase with anaerobic activity. The activity for atmospheric H₂ oxidation was regenerated during incubation in H₂-free atmospheres, especially in the presence of oxygen. Inhibition and regeneration were probably due to alterations in components of the soil hydrogenases caused by the extent of a maximal electron flow through the electron transport system of the soil hydrogenases. Two classes of hydrogenase activities were discerned in eolian sand: one predominantly active under aerobic and the other under anaerobic conditions.