Pineal and locomotor activity

Summary Perch-hopping activity patterns of pinealectomized and normal house sparrows,Passer domesticus, were examined by power spectral analysis and by analysis of daily totals. Power spectral analysis strengthened our previous conclusion that circadian periodicity is absent from the activity of pinealectomized birds kept in constant conditions. The spectral analyses also revealed that obvious ultradian rhythms are not present in sparrow perching activity. Pinealectomy had no effect on the daily activity totals.     

Effects of pressed beet pulp silage inclusion in maize-based rations on performance of high-yielding dairy cows and parameters of rumen fermentation

Beet pulp contains high amounts of pectins that can reduce the risk of rumen disorders compared to using feedstuffs high in starch. The objective was to study the effects of inclusion of ensiled pressed beet pulp in total mixed rations (TMR) for high-yielding dairy cows. Two TMR containing no or about 20% (on dry matter (DM) basis) beet pulp silage were used. The beet pulp silage mainly replaced maize silage and corn cob silage. The TMR were intentionally equal in the concentrations of energy and utilisable crude protein (CP) at the duodenum. TMR were fed to 39 and 40 dairy cows, respectively, for 118 days. The average daily milk yield was about 43 kg/day. No significant differences in milk yield and milk fat or milk protein content were detected. DM intake of cows was significantly reduced by the inclusion of beet pulp silage (23.0 v. 24.5 kg/day). However, a digestibility study, separately conducted with sheep, showed a significantly higher organic matter digestibility and metabolisable energy concentration for the TMR that contained beet pulp silage. In vitro gas production kinetics indicated that the intensity of fermentation was lower in the TMR that contained beet pulp silage. In vitro production of short-chain fatty acids, studied using a Rusitec, did not differ between the TMR. However, the inclusion of beet pulp silage in the ration caused a significant reduction in the efficiency of microbial CP synthesis in vitro. The amino acid profile of microbial protein remained unchanged. It was concluded that beet pulp silage has specific effects on ruminal fermentation that may depress feed intake of cows but improve digestibility. An inclusion of beet pulp silage of up to 20% of DM in rations for high-yielding dairy cows is possible without significant effects on milk yield and milk protein or milk fat.     

Insects as vectors of plant pathogens: mutualistic and antagonistic interactions

Interactions between plants and their herbivores and pathogens are mostly analysed separately, thereby neglecting mutualistic or antagonistic interactions between these antagonists and possible joint effects on the host. We studied interactions between the weed Cirsium arvense, the rust fungus Puccinia punctiformis and three herbivorous insects, the aphids Aphis fabae ssp. cirsiiacanthoidis and Uroleucon cirsii, and the beetle Cassida rubiginosa. All three insect species mechanically transported spore material and significantly increased rates of P. punctiformis infection in healthy thistles. The interaction between C. rubiginosa and the fungus was antagonistic. Although C. rubiginosa transferred spores, biomass of adults was significantly reduced, development of adults tended to be prolonged and mortality increased when feeding on plants infected with P. punctiformis. In contrast, the relationship between the aphid U. cirsii and P. punctiformis was mutualistic: U. cirsii profited by fungal infection and formed significantly larger colonies on fungus-infected plants. Although the differences in insect performance suggest that aphids may be better vectors than the beetle, infection rates were similar. This is the first study to demonstrate that the relationship between herbivores, which increase the dispersal of a pathogen, and the pathogen itself can be mutualistic or antagonistic, depending on the species.     

Hepatic tissue engineering: from transplantation to customized cell-based liver directed therapies from the laboratory

Today, liver transplantation is still the only curative treatment for liver failure due to end-stages liver diseases. Donor organ shortage, high cost and the need of immunosuppressive medications are still the major limitations in the field of liver transplantation. Thus, alternative innovative cell-based liver directed therapies, e.g. liver tissue engineering, are under investigation with the aim, that in future an artificial liver tissue could be created and be used for the replacement of the liver function in patients. Using cells instead of organs in this setting should permit (i) expansion of cells in an in vitro phase, (ii) genetic or immunological manipulation of cells for transplantation, (iii) tissue typing and cryopreservation in a cell bank, and (iv) the ex vivo genetic modification of patient's own cells prior re-implantation. Function and differentiation of liver cells are influenced by the three-dimensional organ architecture. The use of polymeric matrices permits the three dimensional formation of a neo-tissue and specific stimulation by adequate modification of the matrix-surface which might be essential for appropriate differentiation of transplanted cells. Additionally, culturing hepatocytes on three dimensional matrices permits culture in a flow bioreactor system with increased function and survival of the cultured cells. Based on bioreactor technology, bioartificial liver devices (BAL) are developed for extracorporeal liver support. Although BALs improved clinical and metabolic conditions, increased patient survival rates have not been proven yet. For intra-corporeal liver replacement, a concept which combines Tissue Engineering using three-dimensional, highly porous matrices with cell transplantation could be useful. In such a concept, whole liver mass transplantation, long term engraftment and function as well as correction of a metabolic defect in animal models could be achieved with a principally reversible procedure. Future studies have to investigate, which environmental conditions and transplantation system would be most suitable for the development of artificial functional liver tissue including blood supply for a potential use in a clinical setting.     

Die Rückkehr der Wölfe. Das erste Jahrzehnt

The first decade: the return of the wolves Wolves returned to Saxony in the year 2000 since then they have been regularly rearing pups. Nowadays at least 60‐80 wolves are living in Germany. To face its attendant conflicts a wolf management has been installed including wolf monitoring, public relation work and damage compensation. According to the monitoring wolves feed almost completely on wild ungulates, whereas livestock does not play a major role. The wolves' natural origin from north‐eastern Poland could be proven by genetic analyses. By the use of radiotelemetry important information could be gained on the adaption of the wolves to the anthropogenic landscape.     

Modulation of Cyp3a11 mRNA expression by alpha-tocopherol but not gamma-tocotrienol in mice

Metabolism of vitamin E is initiated by cytochrome P450 (CYP) enzymes usually involved in the metabolism of xenobiotics. Like other CYP substrates, vitamin E induced a reporter gene under the control of the pregnane X receptor (PXR) which regulates the expression of CYPs including CYP3A4. gamma-Tocotrienol, the most effective PXR activator, also induced endogenous CYP3A4 mRNA in HepG2 cells. Since these findings imply an interference of vitamin E with drug metabolism it was deemed necessary to investigate their in vivo relevance. Therefore, mice were grown for 3 months with alpha-tocopherol-deficient, -adequate, and -supranutritional diet, i.e. 2, 20 and 200 mg RRR-alpha-tocopheryl acetate/kg diet, respectively. Half of them received 250 microg gamma-tocotrienol/day for the last 7 days. After 3 months, hepatic levels of Cyp3a11 mRNA, the murine homolog to human CYP3A4, were about 2.5-fold higher in the 20 and 200 mg alpha-tocopherol groups than in the 2 mg group. After feeding 200 mg alpha-tocopherol for 9 months, Cyp3a11 mRNA was 1.7-fold higher than after 3 months. In contrast, gamma-tocotrienol did not induce Cyp3a11 mRNA. This could be explained by its high metabolism as demonstrated by the 20- to 25-fold increase in the urinary excretion of gamma-CEHC, the final metabolite of gamma-tocotrienol degradation. In conclusion, alpha-tocopherol maintains an adequate level of xenobiotic-metabolizing enzymes. If fed in supranutritional dosages, especially for longer times, alpha-tocopherol induces Cyp3a11 to levels which might interfere with drug metabolism.     

Hepatic lineages isolated from developing rat liver show different ways of maturation

Immunocytochemical analysis revealed that different hepatic cell types exist during liver development: (i). cells co-expressing the stem-cell marker Thy1 and the hepatic lineage marker CK-18 and (ii). cells only expressing CK-18 (hepatoblasts). In this study we separated the different hepatic cells and analyzed gene-expression and phenotype. Fetal rat livers were digested by collagenase solution. OX43- and OX44-positive hematopoietic cells were depleted and Thy1-positive cells were enriched using Magnetic cell sorting. The different cell compartments were analyzed by RT-PCR and immunocytochemistry for Thy1, CK-18, AFP, and albumin. Hepatoblasts expressed albumin at all times and AFP in the early stages. Thy1-enriched cells expressed CK-18 at all times, albumin in the early, and AFP in the late stages. Thy1-positive cells from fetal livers express liver specific genes. The data suggest that Thy1-positive hepatic cells develop towards hepatic stem cells, and hepatoblasts develop towards mature hepatocytes of the adult liver.     

Arabidopsis Zinc Ribbon 3 is the ortholog of yeast mitochondrial HSP70 escort protein HEP1 and belongs to an ancient protein family in mitochondria and plastids

ZR proteins belong to a phylogenetically conserved family of small zinc-ribbon proteins in plastids and mitochondria of higher plants. The function of these proteins is so far unclear. The mitochondrial proteins share sequence similarities with mitochondrial Hsp70 escort proteins (HEP) from Saccharomyces cerevisiae (HEP1) and human. Expression of the mitochondrial ZR protein from Arabidopsis, ZR3, rescued a hep1 knockout mutant from yeast. Accordingly, ZR3 was found to physically interact with mitochondrial Hsp70 from Arabidopsis. Our findings support the idea that mitochondrial and plastidic ZR proteins from higher plants are orthologs of HEP proteins.

Structured summary of protein interactions

ZR3physically interacts with mtHSC70-2 by pull down (View interaction)ZR3physically interacts with mtHSC70-1 by pull down (View interaction)     

Modulation of pregnane X receptor- and electrophile responsive element-mediated gene expression by dietary polyphenolic compounds

Based on animal models, dietary polyphenols are predicted to be promising chemopreventive agents in humans. Allspice, clove, and thyme extracts as well as defined dietary polyphenolic compounds were, therefore, tested for their ability to activate mechanisms related to phase 1 enzymes, i.e., the PXR-regulated CYP3A4 promoter, and phase 2 enzymes, i.e. the EpRE-regulated promoters of gastrointestinal glutathione peroxidase (GI-GPx) and heme oxygenase-1 (HO-1), examples of Nrf2-regulated genes. From the compounds tested, clove and thyme extracts as well as curcumin and resveratrol activated the PXR. PXR activation correlated with the activation of the CYP3A4 promoter in the case of thyme extract, curcumin, and resveratrol, but not in the case of clove extract. Allspice extract, EGCG, and quercetin did not activate PXR but enhanced CYP3A4 promoter activity. Thyme extract and quercetin activated the EpRE of HO-1. Both significantly activated the GI-GPx promoter, effects that depended on a functional EpRE. Resveratrol did not activate the isolated EpRE but enhanced the GI-GPx promoter activity, whereas clove extract even inhibited it. It is concluded that individual polyphenols as well as polyphenol-rich plant extracts may affect phase 1 and 2 enzyme expression by distinct mechanisms that must be elucidated, before potential health effects can reliably be predicted.