Evolutionary conservation of the 3′ ends of members of a family of giant secretory protein genes inChironomus pallidivittatus

Summary Two cDNA clones representing the 3-end regions of BR1 and BR2 75S mRNA were obtained fromChironomus pallidivittatus. The regular structure characterizing the core of these genes, consisting of tandemly arranged repeat units, changes into a more irregular structure toward the 3 end. Distal to a standard type of repeat unit with a characteristic excess of positive charges, a new type of repeat with a high, negative charge density is interspersed among parts of the standard unit. The last 111 amino acids before the stop codon represent a unique region distinctly different in amino acid composition from upstream regions, and include two partially homologous hydrophobic regions. Sequence comparison of 3-end regions from clones representing BR1 and BR2 genes indicates striking sequence conservation in the unique part of the region. Analysis of the level of silent site divergence shows that the homology increases in the 3 direction up to the polyadenylation site. That the unique region is retained as a part of the secreted protein is shown by Western blotting.     

Transport of Mg2+ and Ca2+, and Mg2+-stimulated adenosine triphosphatase activity in oat roots as affected by mineral nutrition

Mg²⁺- and Ca²⁺-uptake was measured in dark-grown oat seedlings ( Avena sativa L. cv. Brighton) cultivated at two levels of mineral nutrition. In addition the stimulation of the ATPase activity of the microsomal fraction of the roots by Mg²⁺ was measured. Ca²⁺-uptake by the roots was mainly passive. Mg²⁺-uptake mainly active; the passive component of Mg²⁺-uptake was accompanied by Ca²⁺-efflux up to 60% of the Ca²⁺ present in the roots.
In general Mg²⁺ -uptake of oat roots was biphasic. The affinity of the second phase correspond well with that of the Mg²⁺-stimulation of the ATPase activity, in low-salt roots as well as in high-salt roots and in roots of plants switched to the other nutritional condition. Linear relationships were observed when [phase 2] Mg²⁺-uptake was plotted against Mg²⁺-stimulation of the ATPase activity of the microsomal fraction of the roots. In 5 days old high-salt plants 1 ATP (hydrolysed in the presence of Mg²⁺ J corresponded with active uptake of a single Mg²⁺ ion, but in older high-salt roots and in low-salt roots more ATP was hydrolysed per net uptake of a Mg²⁺ ion. The results are discussed against the background of regulation of the Mg²⁺-level of the cytoplasm of root cells by transport of Mg²⁺ by a Mg²⁺-ATPase to the vacuole, to the xylem vessels, and possibly outwards.     

Inhibition of axonal transport in vitro in frog sciatic nerves by chlorpromazine and lidocaine

Summary The effects of chlorpromazine hydrochloride (CPZ HCl) and prochlorperazin-metansulfonate (PCPZ) on the fast axonal transport of labelled proteins were examined in vitro in a peripheral frog nerve.A 0.1 mM concentration of CPZ HCl and PCPZ reduced the amount of transported proteins by more than 50 per cent. An almost complete block was obtained with a 0.5 mM concentration of these two drugs. The lower concentration hardly affected the protein synthesis. The transport inhibiting effect of 0.1 mM of the drugs was reversible but not that of the higher concentration.The number of microtubuli was strongly decreased and the number of filaments increased at the transport inhibiting concentrations. The ultrastructural changes induced by 0.1 mM of the phenothiazine tranquilizer were largely reversible. The local anesthetics lidocaine (18.3 mM) and tetracaine (3.3 mM) both caused similar changes, i.e. a reduction in the number of microtubuli. No ultrastructural effects were observed after treatment with 1 mM ouabain. These three drugs are known to block the axonal flow in the present system at the above mentioned concentrations.The biochemical and ultrastructural results are discussed in relation to those induced by other drugs affecting axonal transport.The present work was supported by grants from Statens Naturvetenskapliga Forskningsråd (No. 2535-8), C.-B. Nathorsts Vetenskapliga och Allmännyttiga Stiftelser, the Swedish Medical Research Council (B73-12X-2543-05B), H. Hierta's Stiftelse and W. och M. Lundgrens Stiftelse. Thanks are due to Mrs B. Egnér, Mrs E. Fjällstedt, Mrs. E. Norström and Mrs U. Svedin for expert technical assistance.     

Chromatin structure of a hyperactive secretory protein gene (in Balbiani ring 2) of Chironomus

We examined the chromatin structure of a Balbiani ring (secretory protein gene) in the salivary glands of Chironomus larvae in its hyperactive state after stimulation with pilocarpine. For the inactive state of the gene an established tissue culture cell line, not expressing the gene, was used. Electron microscopy showed an RNA polymerase density of approximately 38/microns. Micrococcal nuclease digestion of purified nuclei followed by DNA transfer and hybridization revealed a smear with no recognizable discrete DNA fragments. Without pilocarpine stimulation a faint nucleosomal repeat was superimposed upon the smear, and in tissue culture cells a clear nucleosomal repeat was revealed. The restriction enzyme XbaI, which has a 6-bp recognition sequence, cut the gene in the hyperactive chromatin state, but not in its inactive conformation. The combined results are best explained by the absence of most of the nucleosomes in this hyperactive RNA polymerase II transcribed gene.     

Secondary chemistry and ribosomal DNA data congruencies in Arnica (Asteraceae)

To investigate possible congruencies between DNA sequence data and secondary chemistry, we compared nuclear ribosomal DNA (nrDNA) sequence data, sesquiterpene lactone (STL) contents, and cytometric data from 35 accessions of 16 Arnica (Asteraceae) species and two outgroup taxa ( Layia hieracioides and Madia sativa ), using phylogenetic inference and principal component analysis (PCA). Several groups supporting multiple accessions of the same species (of A. montana , A. longifolia , A. gracilis , and A. chamissonis ) are congruent between the phylogenetic trees based on nrDNA and STL data. Sesquiterpene lactone profiles were found to be highly consistent within multiple samples of A. montana and A. longifolia respectively . Moreover, sesquiterpene lactone data support subspecies classifications of A. chamissonis and A. parryi , with additional support from DNA sequence data and cytometric data. Morphology, STL data (PCA), cytometric data and DNA sequence data suggest a hybrid origin of one accession ( A. gracilis  ×  longifolia ). In A. gracilis , A. latifolia , and Layia hieracioides , previously not investigated for STLs, we found large amounts of xanthalongin derivatives. This is the first time STLs have been reported from subtribe Madiinae.
© The Willi Hennig Society 2009.     

The brain 5-HT4 receptor binding is down-regulated in the Flinders Sensitive Line depression model and in response to paroxetine administration

The 5-hydroxytryptamine (5-HT₄) receptor may be implicated in depression and is a new potential target for antidepressant treatment. We have investigated the brain 5-HT₄ receptor [³H]SB207145 binding in the Flinders Sensitive Line rat depression model by quantitative receptor autoradiography, and related this to 5-HT transporter ( S )-[ N -methyl-³H]citalopram binding. We also determined the regulation of 5-HT₄ receptor binding by 1, 14, and 21 days of paroxetine administration and subchronic 5-HT depletion, and compared this with changes in 5-HT_2A receptor [³H]MDL100907 binding. In the Flinders Sensitive Line, the 5-HT₄ receptor and 5-HT transporter binding were decreased in the dorsal and ventral hippocampus, and the changes in binding were directly correlated within the dorsal hippocampus. Chronic but not acute paroxetine administration caused a 16–47% down-regulation of 5-HT₄ receptor binding in all regions evaluated including the basal ganglia and hippocampus, while 5-HT depletion increased the 5-HT₄ receptor binding in the dorsal hippocampus, hypothalamus, and lateral globus pallidus. In comparison, the 5-HT_2A receptor binding was decreased in the frontal and cingulate cortices after chronic paroxetine administration, and markedly reduced in several regions after 5-HT depletion. Thus, the 5-HT₄ receptor binding was decreased in the Flinders Sensitive Line depression model and in response to chronic paroxetine administration.