Molecular Cloning and Expression of a Human Phosphodiesterase 4C

A cDNA coding for a human phosphodiesterase 4C (PDE4C2) was isolated from the mRNA prepared from the glioblastoma cell line, U87. The cDNA contained an ORF of 1818 bp corresponding to a 605 amino acid polypeptide. The sequence differed at the 5′ end from the human PDE4C previously reported (Engels, P. et al, 1995 FEBs Letters 358, 305-310) indicating that it represents a novel splice variant of the human PDE4C gene. Evidence was also obtained for a third 5′ splice variant. The PDE4C2 cDNA was transfected into both COS 1 cells and yeast cells, and shown to direct the expression of an 80 kD polypeptide by Western blotting using a PDE4C specific antiserum. The activity of cell lysates was typical of PDE4 being specific for cAMP and inhibitable by the selective inhibitor, rolipram. However, the K_m for cAMP of the enzyme produced in COS cells was 0.6 μM compared to 2.6 μM for the yeast 4C activity. In addition the COS cell PDE4 activity was much more sensitive to R rolipram than the yeast PDE4 enzyme (IC₅₀ of 23 nM compared to 1648 nM). This difference in rolipram sensitivity was associated with the detection of a high affinity [³H] R rolipram binding site on the COS cell 4C enzyme but not on the yeast expressed enzyme. The results indicate that the enzyme can adopt more than one active conformation, which are distinguished by their interaction with rolipram.     

Methodological approach for the assessment of environmental effects of agroforestry at the landscape scale

Silvoarable agroforestry, the deliberate combined use of trees and arable crops on the same area of land, has been proposed in order to improve the environmental performance of agricultural systems in Europe. Based on existing models and algorithms, we developed a method to predict the environmental effects of SAF at a farm and landscape scale. The method is comprised of an assessment of soil erosion, nitrogen leaching, carbon sequestration, and landscape diversity and allowed the comparison of the environmental performance of SAF with arable systems using these four indicators.The method was applied to three landscape test sites of 4 km × 4 km each in Spain, France, and The Netherlands, and compared different levels of agroforestry adoption on farmland of different potential productivity. Silvoarable agroforestry was predicted to reduce soil erosion by up to 70%, to reduce N leaching by 20–30%, to increase C sequestration over 60 years by up to 140 tonnes C ha⁻¹, and to increase landscape diversity up to four times. The method developed was executed with widely available landscape and farm structural data and can therefore be applied to other regions in order to obtain a broader assessment of the environmental performance of silvoarable agroforestry systems.     

Physiologische und biochemische Beiträge zur Taxonomie der GattungChlorella

Salt tolerance was found to be a species-specific character in the genus Chlorella. The most resistant species, C. luteoviridis, is able to grow in nutrient media containing up to 5% NaCl. The limit for C. protothecoides and C. saccharophila is at 4% NaCl. C. vulgaris var. vulgaris, C. fusa var. vacuolata and C. fusca var. rubescens grow in the presence of 3%, and C. fusca var. fusca, C. kessleri and C. vulgaris f. tertia in the presence of 2% NaCl. C. zofingiensis and C. minutissima are only capable of growing in media containing up to 1% NaCl, and C. homosphaera does not even tolerate 1% NaCl. Those strains, which are able to synthesize secondary carotenoids, turn orange in salt concentrations close to the limit of their tolerance.     

Die Verteilung der Haptoglobin-Phänotypen und Haptoglobin-Allele bei der Lungentuberkulose

Summary The frequency of the three most common haptoglobin-phenotypes and haptoglobin-alleles has been determined in 684 propositi with pulmonary tuberculosis. The distribution in this disease has been compared with 685 serum samples of healthy inhabitants of Süd-Niedersachsen with a Hp¹ frequency of 0.4058. The frequency of the gene Hp¹ in pulmonary tuberculosis is 0.4232, in open pulmonary tuberculosis (n=328) 0.4278 and in closed pulmonary tuberculosis (n=356) 0.4199. The differences are statistically not significant in the several comparsions. There are no correlations between serum haptoglobins and pulmonary tuberculosis.

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(Direktor: Prof. Dr. med. P. E. Becker)     

A functional Wood–Ljungdahl pathway devoid of a formate dehydrogenase in the gut acetogens Blautia wexlerae,Blautia luti and beyond

Species of the genus Blautia are typical inhabitants of the human gut and considered as beneficial gut microbes. However, their role in the gut microbiome and their metabolic features are poorly understood. Blautia schinkii was described as an acetogenic bacterium, characterized by a functional Wood–Ljungdahl pathway (WLP) of acetogenesis from H₂ + CO₂. Here we report that two relatives, Blautia luti and Blautia wexlerae do not grow on H₂ + CO₂. Inspection of the genome sequence revealed all genes of the WLP except genes encoding a formate dehydrogenase and an electron-bifurcating hydrogenase. Enzyme assays confirmed this prediction. Accordingly, resting cells neither converted H₂ + CO₂ nor H₂ + HCOOH + CO₂ to acetate. Carbon monoxide is an intermediate of the WLP and substrate for many acetogens. Blautia luti and B. wexlerae had an active CO dehydrogenase and resting cells performed acetogenesis from HCOOH + CO₂ + CO, demonstrating a functional WLP. Bioinformatic analyses revealed that many Blautia strains as well as other gut acetogens lack formate dehydrogenases and hydrogenases. Thus, the use of formate instead of H₂ + CO₂ as an interspecies hydrogen and electron carrier seems to be more common in the gut microbiome.