Bioenergie aus Knöterich und Kuhmist

Bioenergy from Fallopia japonica and cow dung This article investigates whether Fallopia japonica, a rampant neophyte in Germany, is a suitable alternative to maize as an energy crop. To this end, parts of the plant which had been harvested overground were shredded, fermented in a Hohenheim Biogas Yield Test and the amount of methane produced thereby was determined. The results indicate that Fallopia japonica yields values which are comparable to the results obtained for maize and thus represents a possible alternative as an energy crop. Thus a weed could be controlled and put to an ecologically and economically efficient use. This study was carried out within student the competition by the Siemens Foundation and awarded a prize.     

Maternal and paternal lineages in cross-breeding bovine species. Has wisent a hybrid origin?

The tribe Bovini comprises cattle and cattle-like species. Reconstructions of their phylogeny have so far been incomplete and have yielded conflicting conclusions about the relationship of American bison and wisent (European bison). We have compared the sequences of three mitochondrial and two Y-chromosomal DNA segments. Mitochondrial DNA indicates that four distinct maternal lineages diverged after an early split-off of the buffalo species, leading to (1) taurine cattle and zebu, (2) wisent, (3) American bison and yak, and (4) banteng, gaur, and gayal, respectively. At a higher level, lineages (1) and (2) and lineages (3) and (4) are probably associated. In contrast, Y-chromosomal sequences indicate a close association of American and European bison, which is in agreement with their morphological similarity, complete fertility of hybrid offspring, and amplified fragment length polymorphism (AFLP) fingerprints of nuclear DNA. One explanation for the anomalous divergence of the mitochondrial DNA from the two bison species is lineage sorting, which implies that two distinct mitochondrial lineages coexisted in the bison-yak branch until the recent divergence of American bison and wisent. Alternatively, the wisent may have emerged by species hybridization initiated by introgression of bison bulls in another ancestral species. This "transpatric" mode of species formation would be consistent with the recent appearance of the wisent in the fossil record without clearly identifiable ancestors.