University of Hohenheim

About: University of Hohenheim is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Population & Soil water. The organization has 8585 authors who have published 16406 publications receiving 567377 citations.

Primary succession of soil Crenarchaeota across a receding glacier foreland

Abstract: The development of soil archaeal community structures in relation to primary succession in bulk and rhizosphere soil was examined across the forefield of the receding Rotmoosferner glacier in Austria. Using cloning and denaturing gradient gel electrophoresis (DGGE) analysis of reverse transcription polymerase chain reaction (RT-PCR) products of extracted 16S rRNA, archaeal community structure was compared over a chronosequence representing approximately 150 years of soil development and to reference sites outside the glacier forefield, representing soil exposed for approximately 9500 years. Archaeal community composition was found to be dominated by members of the non-thermophilic or Group 1 Crenarchaeota, where a dramatic yet highly structured successional sequence was observed. Succession over the 150 years sequence could be identified as occurring in three stages, each of which had a phylogenetically distinct 1.1b crenarchaea community with those organisms present in pioneering and intermediate stages belonging to a lineage distinct from those in developed soils. Climax communities also contained organisms belonging to three other major non-thermophilic crenarchaeal lineages. Comparison of archaeal communities in the rhizosphere indicated that plant species composition was not the major driver of specific crenarchaeal populations. These results indicate the potential role of soil crenarchaea in the development of soil substrates, as well as ecological diversity within and between major Group 1 lineages.

A Putative Function for the Arabidopsis Fe–Phytosiderophore Transporter Homolog AtYSL2 in Fe and Zn Homeostasis

Abstract: Although Arabidopsis thaliana does not produce phytosiderophores (PS) under Fe deficiency, it contains eight homologs of the metal-PS/metal-nicotianamine (NA) transporter ZmYS1 from maize. This study aimed to investigate whether one of the closest Arabidopsis homologs to ZmYS1, AtYSL2, is involved in metal-chelate transport. Northern analysis revealed high expression levels of AtYSL2 in Fe-sufficient or Fe-resupplied roots, while under Fe deficiency transcript levels decreased. Quantitative real-time polymerase chain reaction (PCR) and analysis of transgenic plants expressing an AtYSL2 promoter::beta-glucuronidase gene further allowed the detection of down-regulated AtYSL2 gene expression under Zn and Fe deficiency. In contrast to ZmYS1, AtYSL2 did not mediate metal-PS or metal-NA transport in yeast mutants defective in Cu or Fe uptake, nor did AtYSL2 mediate Fe(II)-NA-, Fe(III)-NA- or Ni(II)-NA-inducible currents when assayed by two-electrode voltage clamp in Xenopus oocytes. Moreover, truncation of the N-terminus to remove putative phosphorylation sites that might trigger autoinhibition did not confer functionality to AtYSL2. A direct growth comparison of yeast cells transformed with AtYSL2 in two different yeast expression vectors showed that transformation with empty pFL61 repressed growth even under non-limiting Fe supply. We therefore conclude that the yeast complementation assay previously employed does not allow the identification of AtYSL2 as an Fe-NA transporter. Transgenic plants expressing an AtYSL2 promoter::beta-glucuronidase gene showed expression in root endodermis and pericycle cells facing the meta-xylem tubes. Taken together, our investigations support an involvement of AtYSL2 in Fe and Zn homeostasis, although functionality or substrate specificity are likely to differ between AtYSL2 and ZmYS1.

Detection and direct genomic sequencing of multiple rare unknown flanking DNA in highly complex samples.

Abstract: By identifying the sequence of retro- and lentiviral integration sites in peripheral blood leukocytes, the clonal composition and fate of genetically modified hematopoietic progenitor and stem cells could be mapped in vitro and in vivo. Previously available methods have been limited to the analysis of mono- or oligoclonal integration sites present in high copy numbers. Here, we perform characterization of multiple rare retroviral and lentiviral integration sites in highly complex DNA samples. The reliability of this method results from nontarget DNA removal via magnetic extension primer tag selection (EPTS) preceding solid-phase ligation-mediated PCR. EPTS/LM-PCR allowed the simultaneous direct genomic sequencing of multiple proviral LTR-flanking sequences of retro- and lentiviral vectors even if only 1 per 100 to 1000 cells contained the provirus. A primer walking "around" the integration locus demonstrated the adaptability of EPTS/LM-PCR to study unknown flanking DNA regions unrelated to proviruses. The technique is fast, inexpensive, and sensitive in minimal samples. It enables studies of retro- and lentiviral integration, viral vector tracking in gene therapy, insertional mutagenesis, transgene integration, and direct genomic sequencing that until now have been difficult or impossible to perform.

Purine quantification in digesta from ruminants by spectrophotometric and HPLC methods.

Abstract: The method of Zinn & Owens (1986; Canadian Journal of Animal Science 66, 157-166), based on release of purine bases by HClO4 followed by their precipitation with AgNO3, was used to study recovery of purines from lyophilized rumen microbial or Escherichia coli preparations added to matrices such as cellulose, starch and neutral-detergent fibre. The recovery of purines was poor (approximately 50%). Under the hydrolysis conditions (12 M-HClO4, 90-95 degrees for 1 h) used in the method of Zinn & Owens (1986), the recovery of purines from the rumen microbial preparations added to matrices measured using an HPLC method was 95-102%, suggesting that the lower recovery of purines in the method of Zinn & Owens (1986) was not due to incomplete hydrolysis of nucleic acids. Using the HPLC method, adenine and allopurinol (an internal standard) were found to be heat-labile as substantial destruction was observed on heating at 121 degrees. On the other hand, another commonly used internal standard, caffeine, was stable at 121 degrees. A complete hydrolysis of nucleic acids from the rumen microbial preparation was observed with 2.5 ml 0.6 M-HClO4 in a total volume of 3 ml (0.5 M-HClO4 during hydrolysis) at 90-95 degrees for 1 h, and under these conditions adenine, guanine, allopurinol and caffeine were stable. Moreover, under these milder hydrolysis conditions, the recovery of purine bases from the rumen microbial or E. coli preparations added to matrices ranged from 92 to 108% using the method of Zinn & Owens (1986). Based on the results, changes in hydrolysis conditions have been proposed for accurate determination of purine bases using spectrophotometric or HPLC methods.

Greenhouse gas emissions from animal houses and manure stores

Abstract: In contrast to ammonia few data about the emissions of CH4, N2O and CO2 from animal houses are yet available. To be reliable, such data should derive from investigations meeting the following minimum requirements: (1) continuous measurement of ventilation rates and gas concentrations; (2) long-term experiments, to cover diurnal and seasonal effects; (3) use of extremely exact measuring equipment. A literature review has shown that reliable data about CH4 emissions are basically only available for cattle housing systems. Data about N2O emissions from animal houses are lacking, because of the difficulties in measuring very low N2O concentrations. However, the results of existing investigations are not comparable and most of them do not meet the minimum requirements mentioned above. Our own experiments have been carried out for dairy cows in loose housing with natural ventilation. The amount of CH4 originating from cows' digestion is about 223 g per livestock unit (1 LU = 500 kg live-weight) per day and varies between 200 and 250 g per LU per day. It mainly depends on the feed intake, which is positively related to animal size, growth rate and production. There is practically no influence of outside conditions on the emission rate. N2O was emitted at about 1.6 g per LU per day.