The perennial taxa ofCrucianella (Rubiaceae) in SW. Asia and their eco-geographical differentiation

The perennial taxa ofCrucianella in Asia form a coherent group, apparently diploid (x = 11) and outbreeding throughout, and should be placed into sect.Roseae. This Irano-Turanian group has its centre of diversity in the mountain systems south of the Caspian Sea and reaches with outposts NE. and E. Anatolia, NE. Iraq, S. Iran and C. Asia. Four species and 13 subspecies (within the polymorphicC. gilanica) are recognized, described (partly as new), and illustrated (Figs. 1–6). Conspectus, keys and distribution maps (Figs. 7 and 8) as well as plesio- and apomorphic character states and data on size of areas are provided (Table 1). There is an obvious correlation between more plesiomorphic taxa with smaller areas in the distribution centre of the group, and more apomorphic taxa with larger areas towards its periphery (Fig. 9). These findings are linked to a working hypothesis on the evolution of the group.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday.     

Tumor necrosis factor signal transduction. Tissue-specific serine phosphorylation of a 26-kDa cytosolic protein

Binding of tumor necrosis factor-alpha (TNF-alpha) to its receptor on U937 cells results in rapid and TNF dose-dependent phosphorylation of a cytosolic protein with an apparent molecular mass of 26,000 kDa (p26) and an isoelectric point of 5.6. Half-maximal phosphorylation of p26 was achieved at concentrations of 1.8 ng/ml and was detectable within 20 s of TNF-alpha treatment. p26 is phosphorylated exclusively at serine residues. p26 phosphorylation occurs at 37 degrees C as well as at 14 degrees C, indicating that internalization of the TNF receptor is not required for serine kinase activation. Dephosphorylation of p26 starts 10 min after TNF-induced phosphorylation, suggesting a possible regulatory function of this cytosolic protein within the post-TNF receptor signaling system. p26 is also phosphorylated upon treatment with lymphotoxin. In contrast, both interferon-gamma and lipopolysaccharide fail to induce p26 phosphorylation. Whereas phosphorylated p26 was detected in the TNF-sensitive breast cancer cell line CRL1500, other TNF-responsive tumor cell lines investigated lacked enhanced phosphorylation of p26 in response to TNF, indicating that the 26-kDa phosphoprotein (pp26) may be a cell type-specific second messenger molecule involved in TNF signal transduction in some, but not all, target cells. p26 is also phosphorylated in a subclone of U937 (U937.C27) that responds to TNF-alpha with differentiation, yet is resistant to TNF-alpha-mediated growth inhibition. In contrast, p26 is not phosphorylated in another U937 derivative (U937.G3) that is resistant to both TNF-alpha-induced growth arrest and differentiation, suggesting that pp26 may play a role in the TNF signaling pathway linked to differentiation processes rather than to growth control.     

Inversion of gravitropism by symmetric blue light on the clinostat

Gravitropic stimulation of maize (Zea mays L.) seedlings resulted in a continuous curvature of the coleoptiles in a direction opposing the vector of gravity when the seedlings were rotated on a horizontal clinostat. The orientation of this response, however, was reversed when the gravitropic stimulation was preceeded by symmetric preirradiation with blue light (12.7 mol photons·m^–2). The fluence-response curve of this blue light exhibited a lower threshold at 0.5 mol·m^–2, and could be separated into two parts: fluences exceeding 5 mol·m^–2 reversed the direction of the gravitropic response, whereas for a range between the threshold and 4 mol·m^–2 a split population was obtained. In all cases a very strong curvature resulted either in the direction of gravity or in the opposite orientation. A minor fraction of seedlings, however, curved towards the caryopsis. Furthermore, the capacity of blue light to reverse the direction of the gravitropic response disappeared with the duration of gravitropic stimulation and it depended on the delay time between both stimulations. Thistonic blue-light influence appears to be transient, which is in contrast to the stability observed fortropistic blue-light effects.This work was supported by the Deutsche Forschungsgemeinschaft.     

A cyclic AMP response element mediates repression of tyrosine aminotransferase gene transcription by the tissue-specific extinguisher locus Tse-1

Tyrosine aminotransferase (TAT) gene expression is liver specific and inducible by glucocorticoids and via the cAMP signaling pathway. In fibroblasts and other nonliver cells the gene is subject to negative control by the trans-dominant tissue-specific extinguisher locus Tse-1. We identified a hepatocyte-specific enhancer that is repressed by Tse-1. Two distinct sequence motifs are absolutely essential for function of this enhancer: a cAMP response element (CRE), which is the target for repression by Tse-1, and a hepatocyte-specific element. The specificity of the enhancer is generated by the combination of these two essential elements, which are fully interdependent. In vivo footprinting indicates that Tse-1 acts by affecting protein binding at the CRE. A direct antagonism between Tse-1 and the cAMP signaling pathway suggests that Tse-1 plays a role in control of developmental activation of the TAT gene.     

Hypervariability of intronic simple (gt)n(ga)m repeats in HLA-DRB genes

We have investigated the extent of DNA variability in intronic simple (gt)_n(ga)_m repeat sequences and correlated this to sequence polymorphisms in the flanking exon 2 of HLA-DRB genes. The polymerase chain reaction (PCR) was used to amplify a DNA fragment containing exon 2 and the repeat region of intron 2. The PCR products were separated on sequencing gels in order to demonstrate length hypervariability of the (gt)_n(ga)_m repeats. In a parallel experiment, the PCR products were cloned and sequenced (each exon 2 plus adjacent simple repeats) to characterize the simple repeats in relation to the HLA-DRB sequences. In a panel of 25 DRB1, DRB4, and DRB5 alleles new sequences were not detected. Restriction fragment length polymorphism (RFLP) subtyping of serologically defined haplotypes corresponds to translated DNA sequences in 85% of the cases, the exceptions involving unusual DR/DQ combinations. Many identical DRB1 alleles can be distinguished on the basis of their adjacent simple repeats. We found group-specific organization of the repeats: the DRw52 supergroup repeats differ from those of DRB1*0101, DRB4*0101, and DRB5*0101 alleles and from those of pseudogenes. Finally, we amplified baboon DNA and found a DRB allele with extensive similarity to DRB1 sequences of the DRw52 supergroup. The simple repeat of the baboon gene, however, resembles that of human pseudogenes. In addition to further subtyping, the parallel study of polymorphic protein and hypervariable DNA alleles may allow conclusions to be drawn on the relationships between the DRB genes and perhaps also on the theory of trans-species evolution.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number M 34258.     

Effects of calyculin A on amylase release in streptolysin-O permeabilized acinar cells.

The effects of the phosphatase inhibitors calyculin A and okadaic acid on amylase release from streptolysin-O permeabilized rat pancreatic acini were investigated. Both agents induced similar biphasic effects with moderate potentiation of calcium-stimulated amylase release at medium and strong inhibition at higher concentrations. Calyculin A was thirty times more potent than okadaic acid and at 100 nM totally inhibited calcium-induced amylase release while 3 microM okadaic acid reduced amylase release by 78%. 100nM calyculin A also completely inhibited GTP gamma S-potentiated amylase release and partially inhibited phorbol ester potentiated secretion. The data indicate that inhibition of a serine/threonine phosphatase, probably a type 1 phosphatase, leads to inhibition of calcium-induced amylase release in permeabilized pancreatic acini.     

Changes of membrane phospholipid composition of human erythrocytes in hyperlipidemias. II. Increases in distinct molecular species of phosphatidylethanolamine and phosphatidylcholine containing arachidonic acid.

The molecular species composition of red blood cell diacyl-phosphatidylcholine (PC), diacyl-phosphatidylethanolamine (PE) and alkenylacyl-PE (plasmalogen PE) has been analyzed in normolipidemic and hyperlipidemic donors. In all three phospholipid subclasses the percentages of the species 16:0/20:4 were increased in hyperlipidemic patients. In diacyl-PE, 18:1/20:4 was also elevated. No changes were observed in the other quantitatively important molecular species containing arachidonic acid at sn-2, namely 18:0/20:4. The rise in 16:0/20:4 in diacyl-PC and diacyl-PE of hyperlipidemic donors was accompanied by a fall in molecular species with linoleic acid (18:2) at sn-2 (in particular 18:1/18:2). In alkenylacyl-PE the elevation of 16:0/20:4 was compensated by a decrease in species with docosatetraenoic acid (22:4) at sn-2 in particular by a fall in 16:0/22:4. Among all donors, the percentages of 16:0/20:4 in diacyl-PC and PE were positively associated with plasma total cholesterol levels. The changes in molecular species composition of PC and PE in hyperlipidemia are expected to alter the function of erythrocyte membrane transport proteins and--if present also in other cell types--to affect eicosanoid metabolism.     

d-Ribulokinase from Klebsiella pneumoniae for continuous production of d-(−)-ribulose-5-phosphate

Summary The production of d-ribulose-5-phosphate in an enzyme membrane reactor was examined. Phosphoryl transfer from ATP to d-ribulose was catalysed by d-ribulokinase isolated from Klebsiella pneumoniae. For production of d-ribulose-5-phosphate the phosphoryl donor ATP was used either in stoichiometric or in catalytic amounts. Using catalytic amounts of ATP requires a second enzyme, e.g. pyruvate kinase, to regenerate ATP. The kinetic parameters for d-ribulokinase and pyruvate kinase were determined to calculate the performance of an enzyme membrane reactor for continuous production of d-ribulose-5-phosphate. Both processes operated for more than 200 h. Regardless of whether ATP was used in catalytic or stoichiometric amounts, about the same production parameters were determined. In continuous production space/time yields of 117 g (with ATP regeneration) and 103 g (without ATP regeneration) of d-ribulose-5-phosphate 1^–1 per day were reached.Offprint requests to: D. Gygax