The δ18O signatures of HCl‐extractable soil phosphates: methodological challenges and evidence of the cycling of biological P in arable soil

Soil phosphates exchange oxygen atoms rapidly with soil water once recycled by intracellular enzymes, thereby approaching an equilibrium δ¹⁸O_P signature that depends on ambient temperature and the δ¹⁸O_W signature of soil water. We hypothesized that in the topsoil, phosphates reach this equilibrium δ¹⁸O_P signature even if amended by different fertilizers. In the subsoil, however, there might be phosphates with a smaller δ¹⁸O_P value than that represented by the isotopic equilibrium value, a condition that could exist in the case of limited biological P cycling only. We tested these hypotheses for the HCl‐extractable P pool of the Hedley fractionation scheme of arable soil in Germany, which integrates over extended time‐scales of the soil P cycle. We sampled several types of fertilizer, the surface soil that received these fertilizer types and composites from a Haplic Luvisol depth profile under long‐term agricultural practice. Organic fertilizers had significantly smaller δ¹⁸O_P values than mineral fertilizers. Intriguingly, the fields fertilized organically also tended to have smaller δ¹⁸O_P signatures than other types of surface soil, which calls into question full isotopic equilibrium at all sites. At depths below 50 cm, the soil δ¹⁸O_P values were even depleted relative to the values calculated for isotopic equilibrium. This implies that HCl‐extractable phosphates in different soil horizons are of different origins. In addition, it supports the assumption that biological cycling of P by intracellular microbial enzymes might have been relatively inefficient in the deeper subsoil. At depths of 50–80 cm, there was a transition zone of declining δ¹⁸O_P values, which might be regarded as the first evidence that the degree of biological P cycling changed at this depth interval.     

Activated expression of the N-myc gene in human neuroblastomas and related tumors

In neuroblastoma lines in which the N-myc gene is present as a single copy, the expression of N-myc as messenger RNA is increased relative to that in nonneuroblastoma cell lines and tumors. The increase of expression in neuroblastomas with amplified N-myc genes is the result of (i) an increase in the absolute amount of expression of each N-myc gene and (ii) an increase in the copy number of the N-myc gene. A second gene--which is amplified in many of the same lines as N-myc--is expressed to about the same degree in most human cell lines and primary tumors regardless of origin (when normalized to gene copy number). Thus, a change in the regulation of N-myc expression in neuroblastomas and certain other tumors results in greatly increased expression of each N-myc gene copy.     

Use of new immunoglobulin isotype-specific ELISA-systems to detect Salmonella infections in pigs

In Germany, the program for controlling salmonella infections in pigs is based on tests detecting salmonella-lipopolysaccharide (LPS) induced antibodies in meat-juice or blood. These conventional tests which are based on the technology of enzyme-linked immunosorbent assay (ELISA) detect exclusively or mainly immunoglobulin(lg)G antibodies. Meanwhile, novel ELISA systems (WCE-ELISA, 3-Isotype-Screening-ELISA) have been developed, which additionally detect the antibody classes IgM and IgA.This fact enables the registration of fresh salmonella infections (starting with day 5 p.i.) and thus, the distinction between early and older infections.The results show that animals with early salmonella infections appear significantly more often in herds with a high than with a low prevalence. With the newly developed tests this group of animals can be detected much more efficiently and precisely than with the tests used so far. Due to their clearly improved sensitivity the application of the WCE-ELISA and the 3-Isotype-Screening-ELISA in terms of the QS-Salmonella-Monitoring program can therefore significantly improve the selection of farms with potential salmonella excretors. Additionally, the WCE-ELISA can be applied very suitable for the examination of individual animals.     

Development of chronic and acute golden Syrian hamster infection models with Leptospira borgpetersenii serovar Hardjo

The golden Syrian hamster (Mesocricetus auratus) is frequently used as a model to study virulence for several Leptospira species. Onset of an acute lethal infection following inoculation with several pathogenic Leptospira species has been widely adopted for pathogenesis studies. An important exception is the outcome following inoculation of hamsters with live L. borgpetersenii serovar Hardjo, the primary cause of bovine leptospirosis and a cause of human infections. Typically, inoculation of hamsters with L. borgpetersenii serovar Hardjo fails to induce clinical signs of infection. In this study, the authors defined LD(50) and ID(50) for 2 strains of L. borgpetersenii serovar Hardjo: JB197 and 203. Both strains infected hamsters with ID(50) values of approximately 1.5 × 10(2) bacteria yet differed in tissue invasion and interaction with leukocytes, resulting in widely divergent clinical outcomes. Hamsters infected with strain 203 established renal colonization within 4 days postinfection and remained asymptomatic with chronic renal infections similar to cattle infected with serovar Hardjo. In contrast, hamsters infected with strain JB197 developed a rapidly debilitating disease typical of acute leptospirosis common in accidental hosts (eg, humans) with an LD(50) of 3.6 × 10(4) bacteria. Evidence that strain JB197 resides in both extracellular and intracellular environments during hamster infection was obtained. Development of models that result in chronic and acute forms of leptospirosis provides a platform to study L. borgpetersenii pathogenesis and to test vaccines for the prevention of leptospirosis.     

Next Generation Sequencing of Actinobacteria for the Discovery of Novel Natural Products

Like many fields of the biosciences, actinomycete natural products research has been revolutionised by next-generation DNA sequencing (NGS). Hundreds of new genome sequences from actinobacteria are made public every year, many of them as a result of projects aimed at identifying new natural products and their biosynthetic pathways through genome mining. Advances in these technologies in the last five years have meant not only a reduction in the cost of whole genome sequencing, but also a substantial increase in the quality of the data, having moved from obtaining a draft genome sequence comprised of several hundred short contigs, sometimes of doubtful reliability, to the possibility of obtaining an almost complete and accurate chromosome sequence in a single contig, allowing a detailed study of gene clusters and the design of strategies for refactoring and full gene cluster synthesis. The impact that these technologies are having in the discovery and study of natural products from actinobacteria, including those from the marine environment, is only starting to be realised. In this review we provide a historical perspective of the field, analyse the strengths and limitations of the most relevant technologies, and share the insights acquired during our genome mining projects.     

CP-MAS-13C-NMR-Spektren organischer Lagen einer Tangelrendzina

CP-MAS-¹³C-NMR Spectra of a Lithic Cryofolist CP-MAS-¹³C-NMR spectra of the organic layers of a lithic cryofolist show typical changes during litter decomposition and humification. Peaks due to alkyl-C (mainly polymethylene) and carboxyl-C increase, those due to ether-C (carbohydrates), acetal-C and aromatic-C decrease. These results are in agreement with the results obtained from conventional extractive techniques. The aliphatic character is far more pronounced than the aromatic one.