Die Rolle des Ektoderms und Mesoderms bei der Formbildung der Kiemen und Extremitäten von Triton

Ohne Zusammenfassung     

Flavonoidmuster als systematisches Merkmal in der Gattung Populus

Buds of almost every species of popular excrete lipophilic “coating” which contains many flavonoid and related derivatives. The compounds found in this “bud coat” of eighty taxa of Populus have been examined and nearly 30 compounds have been identified and their distribution related to the taxonomy of the genus. In sections Aigeiros and Tacamahaca and hybrids of these, chrysin, galangin and pinocembrin form the major components which, in most cases, are accompanied by lesser amounts of tectochrysin, izalpinin, pinostrobin, galangin-3-methylether and pinobanksin-3-acetate. Variations are shown by presence of apigenin and its monomethyl ethers, kaempferol methyl ethers, rhamnetin, quercetin-3,7- and 3,3′-dimethylether, the unusual flavanone “P4” and two chalcones. Myricetin, genkwanin and kaempferol-7.4′-dimethylether are each found only in one species. In the sections Leuce and Leucoides, the major compounds are cinnamic acid derivatives. Flavonoid patterns, as analysed on polyamide TLC, allow species of the sections Aigeiros and Tacamahaca and some hybrids to be characterized, provided several individuals are examined, It is not possible by this method to differentiate clones within a species.     

Arbuscular mycorrhizal fungi modify nutrient allocation and composition in wheat (Triticum aestivum L.) subjected to heat-stress

Plant and Soil - Livestock grazing is a widely practiced land-use regime that can impose lingering effects on global biogeochemical cycles. However, elucidating the mechanisms of related...     

Overproduction of the proFhuA outer membrane receptor protein of Escherichia coli K-12: isolation,properties, and immunocytochemical localization at the inner side of the cytoplasmic membrane

The fhu operon of Escherichia coli K-12 comprises four genes, termed fhuA,C,D,B, which are involved in the uptake of iron-hydroxamate compounds. The fhuA gene encodes the outer membrane receptor protein. Cells that contained three copies of the fhuACD fragment on the thermoamplifiable plasmid pHK232 accumulated at 37° C large amounts of the proFhuA protein. Most of the overproduced proFhuA protein was not translocated into the outer membrane but instead precipitated at the cytoplasmic side of the inner membrane, presumably at the sites of synthesis. Despite inhibition of export proFhuA synthesis continued.The precipitate formed was sedimented by centrifugation at 8,000xg. The proFhuA protein could be solubilized in 1% sodium dodecyl sulfate. Replacement of sodium dodecyl sulfate by Triton X-100 resulted in a proFhuA protein which exhibited 10% of the phage T5 binding activity of renatured mature FhuA protein. Binding of phage T5 was inhibited by the FhuA-specific ligands ferrichrome, albomycin and colicin M. Limited proteolysis of the isolated pro- and mature form of the FhuA protein with trypsin yielded similar oligopeptide patterns. Addition of ferrichrome affected trypsin cleavage of both proteins in the same way. The common proteolytic intermediates together with phage inactivation indicate a similar conformation of the pro- and mature form.Dedicated to Prof. G. Braunitzer on the occasion of his 60th birthday     

An Arabidopsis ATP-Dependent,DEAD-Box RNA Helicase Loses Activity upon IsoAsp Formation but Is Restored by PROTEIN ISOASPARTYL METHYLTRANSFERASE

Orthodox seeds are capable of withstanding severe dehydration. However, in the dehydrated state, Asn and Asp residues in proteins can convert to succinimide residues that can further react to predominantly form isomerized isoAsp residues upon rehydration (imbibition). IsoAsp residues can impair protein function and can render seeds nonviable, but PROTEIN ISOASPARTYL METHYLTRANSFERASE (PIMT) can initiate isoAsp conversion to Asp residues. The proteins necessary for translation upon imbibition in orthodox seeds may be particularly important to maintain in an active state. One such protein is the large, multidomain protein, Arabidopsis thaliana PLANT RNA HELICASE75 (PRH75), a DEAD-box helicase known to be susceptible to isoAsp residue accumulation. However, the consequences of such isomerization on PRH75 catalysis and for the plant are unknown. Here, it is demonstrated that PRH75 is necessary for successful seed development. It acquires isoAsp rapidly during heat stress, which eliminates RNA unwinding (but not rewinding) competence. The repair by PIMT is able to restore PRH75’s complex biochemical activity provided isoAsp formation has not led to subsequent, destabilizing conformational alterations. For PRH75, an important enzymatic activity associated with translation would be eliminated unless rapidly repaired by PIMT prior to additional, deleterious conformational changes that would compromise seed vitality and germination.     

Generation of methane from textile desizing liquors

A new strategy for the biological transformation of sugar‐containing wastewaters from the textile desizing process to biogas was developed. Here, industrial liquors were separated from the following washing step by squeezing the impregnated fabrics after desizing. These waters exhibit a chemical oxygen demand of 40 g/L and allow a direct use in microbial biogas reactors without further treatment or accumulation. After reaching balanced conditions, the microbes continuously produce biogas. Moreover, the chemical oxygen demand can be reduced up to 75%. This new technology seems to be practicable and even attractive for small‐ and medium‐sized enterprises with an annual cotton production down to 2000 t. At this stage, a reliable eco‐balance of the overall process is still pending. Further investigations will be carried out soon.     

Exudate flavonoids in three persian asteraceae species

Aereal parts of three Asteraceae from Iran have been analysed for exudate flavonoids. Artemisia oliveriana, Pulicaria gnaphalodes and Tanacetum polycephalum are shown to accumulate mostly 6-methoxylated flavonols and flavones as external aglycones.