Structural features of the plastid ribosomal RNA operons of two red algae: Antithamnion sp. and Cyanidium caldarium

The nucleotide sequences of the plastid 16S rDNA of the multicellular red alga Antithamnion sp. and the 16S rDNA/23S rDNA intergenic spacers of the plastid DNAs of the unicellular red alga Cyanidium caldarium and of Antithamnion sp. were determined. Sequence comparisons support the idea of a polyphyletic origin of the red algal and the higher-plant chloroplasts. Both spacer regions include the unsplit tRNA^Ile (GAU) and tRNA^Ala (UGC) genes and so the plastids of both algae form a homogeneous group with those of chromophytic algae and Cyanophora paradoxa characterized by small-sized rDNA spacers in contrast to green algae and higher plants. Nevertheless, remarkable sequence differences within the rRNA and the tRNA genes give the plastids of Cyanidium caldarium a rather isolated position.     

Molecular cloning of the c2 locus of Zea mays, the gene coding for chalcone synthase

Summary The c2 locus of Zea mays, identified as one of the genes affecting anthocyanin biosynthesis, was cloned using the transposable element En (Spm) as a gene tag. The Spm element present at the c2 locus in the autonomously mutating c2-m1 line was isolated using En1 element specific probes. Sequences flanking the element were identified as c2 locus specific and were used to clone the nonautonomous c2-m2 and wild-type alleles. The cloning and analysis of a cDNA complementary to the c2 locus provided evidence that this gene encodes the enzyme chalcone synthase.     

Chemotherapy and trace element levels in blood and tissue of rats implanted with prostate tumor cells

Male Copenhagen rats with transplanted prostatic adeno-carcinoma were treated with different polyamine synthesis inhibitors, such as methylglyoxal-bis-guanylhydrazone (MGBG), erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) combined with 9-β-d-arabin-ofuranosyl-adenine (ARA-A), α-difluoromethyl-ornithine (DFMO), and some of their combinations. Levels of the essential trace elements—copper, zinc, magnesium, iron, selenium, and manganese —have been determined in blood, tumor, kidney, and liver of these animals and are discussed in terms of efficiency of the treatment. MGBG had the strongest effect on trace element levels in tissues of treated animals. MGBG combined with DFMO exhibited the highest antitumor activity of all treatment protocols. Selenium given as selenite with drinking water was used as an adjuvant with the most toxic combination, (ARA-A/EHNA, MGBG). Selenite reduced the toxicity of these therapeutic agents.     

Plasmid rescue - a tool for reproducible recovery of genes from transfected mammalian cells?

Summary The efficient rescue of plasmids containing the thymidine kinase gene (tk) of Herpes simplex virus type I from genetically transformed mouse cells by transformation of bacteria is described. Rescued plasmids contain insertions of calf DNA used as a carrier in the transfection but usually lack portions of plasmid DNA. Deletions generally concern the region spanning from around the PvuII site of pBR322 to within the tetracycline resistance coding sequence, whereas the extent of tk sequence deletion varies, depending on the site of its integration (BamHI or PvuII) into the plasmid. Modelling the rescue process by transformation of bacteria with a mixture of original plasmids and sheared mouse cell DNA clearly demonstrates that deletions are caused by the presence of the mammalian DNA and they probably occur during re-transformation of bacteria before the onset of tetracycline gene expression. Plasmids lacking the Tc^r region are reproducibly rescuable without deletion. Methods for reproducible re-isolation of transferred genes from mammalian cells are discussed.     

Mikrospektralphotometrische Untersuchungen zum Speichermechanismus des kationischen Farbstoffes Chrysoidin durch die lebende und tote Pflanzenzelle

Wie aus Elektrophorese- und spektralphotometrischen Untersuchungen hervorgeht, liegt der kationische Farbstoff Chrysoidin G, je nach dem pH-Wert der wäßrigen Farblösungen, als I-, II-, III- und IV-wertiges Kation und elektroneutrales Farbbasenmolekül vor. Von physiologischer Bedeutung ist nur das I-wertige Kation und das Farbbasenmolekül. Die Unabhängigkeit der Absorptionsmaxima wäßriger Farbstofflösungen mit konstantem pH-Wert von der Farbstoffkonzentration deutet darauf hin, daß Chrysoidin keine Assoziate bildet. In organischen Lösungsmitteln ergibt Chrysoidin G je nach dem Grad der Polarität des Solvens und dem pH-Wert der wäßrigen Phase bei Ausschüttelungs-versuchen unterschiedliche Absorptionskurven. Natriumnucleinat bedingt eine negative Metachromasie; die jeweilige Lage des Maximums wird von der Natriumnucleinatkonzentration bestimmt. Rutin übt keinen wahrnehmbaren Einfluß auf das Absorptionsspektrum aus. Nach einer Vitalfärbung von Oberepidermiszellen der Schuppenblätter von Allium cepa mit Chrysoidin G zeigen das diffus gefärbte Plasma und die darin auftretenden gelben Kugeln übereinstimmende Absorptionsspektren mit einem breiten Bandenmaximum bei ? 420 nm. Der lebende Zellkern färbt sich nicht. Der gefärbte volle Zellsaft der Unterepidermis besitzt ein Maximum bei ? 448 nm. Aus der Lage der Absorptionsmaxima und dem Verlauf der Absorptionskurven kann geschlossen werden, daß die Färbung des lebenden Plasmas auf eine Anreicherung des einwertigen Kations und des Farbbasenmoleküls in polaren Lipoiden beruht, während es sich bei der Färbung des fixierten Zellkerns um eine Bindung des Chrysoidins an Nucleinsäuren handelt. Die Vitalfärbung des vollen Zellsaftes mit Chrysoidin G ist nicht auf den Gehalt der Vakuolen an Flavonolen zurückzuführen, sondern hängt vermutlich vom pH-Wert des Zellsaftes ab.     

Principles and applications of luminescence spectrometry coupled to liquid chromatographic techniques

An overview is presented of the physicochemical basis of luminescence, and its application to the detection of chemicals (drugs, biomedically important compounds, environmentally active substances) in liquid chromatographic systems.     

Effects of overexpression of Pkn2, a transmembrane protein serine/threonine kinase, on development of Myxococcus xanthus.

Pkn2 is a putative transmembrane protein serine/threonine kinase required for normal development of Myxococcus xanthus. The effect of Pkn2 overexpression on development of M. xanthus was examined by expressing pkn2 under the control of a kanamycin promoter. Pkn2 was clearly detected by Western blot (immunoblot) analysis in the overexpression strain (the PKm/pkn2 strain) but could not be detected in the wild-type strain. Overexpressed Pkn2 was located almost exclusively in the membrane fraction, suggesting that Pkn2 is a transmembrane receptor-type protein Ser/Thr kinase. The PKm/pkn2 strain formed fruiting bodies more slowly than the wild-type strain, in contrast to a Pkn2 deletion strain, the delta pkn2 strain, which developed faster than the wild-type strain. However, spore production was reduced in both the PKm/pkn2 and delta pkn2 strains. These data suggest that Pkn2 functions as a negative regulator for fruiting-body formation and that the proper level of Pkn2 is necessary for maximum myxospore yield.     

Phloem translocation of Fe,Cu, Mn,and Zn in Ricinus seedlings in relation to the concentrations of nicotianamine,an endogenous chelator of divalent metal ions,in different seedling parts

During the first 8 days of germination the Ricinus seedling is supplied with all nutrients by the endosperm via phloem transport. In 4- to 8-days-old seedlings the concentrations and contents of Fe, Cu, Mn and Zn, and nicotianamine (NA) in the endosperm, cotyledons, hypocotyl and roots were estimated. From the data obtained translocation rates and flow profiles for the metals were established. The main sink for Fe, Mn and Zn were the cotyledons whereas Cu was mainly imported into the hypocotyl. Maximum flow rates occurred between days 5 and 7, for Zn between days 6 and 8.The time kinetics of NA and divalent metal ion concentrations and contents are interpreted as co-transport. The role of NA as transport vehicle of micronutrients in the sieve tubes is discussed.