Initiation of morphogenic cell-suspension and protoplast cultures of barley (Hordeum vulgare L.)

Cell-suspension cultures were initiated from embryogenic calli of various barley cultivars. Seven fast-growing suspension lines were obtained from four different cultivars (cvs. Dissa, Emir, Golden Promise and Igri). Two of these cell suspensions showed morphogenic capacity. From a cell suspension of cv. Dissa, albino plantlets were regenerated when aggregates were cultured on solid medium. Aggregates of cv. Igri usually stopped differentiation at the globular stage, but occasionally formed scutellum-like structures. Five suspension lines were used for protoplast isolation and culture. Dividing protoplasts were obtained from all lines, but with cv. Igri a few divisions only and no further development were observed. Protoplasts from the various lines differed in the time of first division (2–14 d), division frequency (0.09–70.9%) and efficiency of colony formation (0.09–7.3%). Protoplasts isolated from the morphogenic cell suspension of cv. Dissa developed compact calli which sporadically regenerated albino plantlets.Abbreviations CC, MS, N6, SH, Kao8p culture media; see Material and methods - cv chltivar - dicamba 3,6-dichloro-o-anisic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - picloram 4-amino-3,5,6-trichloropicolinic acid     

A link of Ca<Superscript>2+</Superscript> to cAMP oscillations in <Emphasis Type="Italic">Dictyostelium</Emphasis>: the calmodulin antagonist W-7 potentiates cAMP relay and transiently inhibits the acidic Ca<Superscript>2+</Superscript>-store

Background  

During early differentiation of Dictyostelium the attractant cAMP is released periodically to induce aggregation of the cells. Here we pursue the question whether pulsatile cAMP signaling is coupled to a basic Ca²⁺-oscillation.     

Some new aspects of 17alpha-estradiol metabolism in man

17Alpha-estradiol (1,3,5(10)-estratriene-3,17alpha-diol) together with a tracer dose of the tritium-labeled compound was administered orally and sublingually to male volunteers. The serum concentrations of 17alpha-estradiol (free and liberated by enzymatic hydrolysis) were quantified by GC/MS, and the serum total radioactivity and urinary radioactivity excretion were determined. After oral administration, 17alpha-estradiol was rapidly and intensively conjugated; only tiny quantities of the free steroid (<1% of total) appeared in serum. Sublingual administration resulted in temporary (up to 3 h p.a.) higher serum levels of the free compound. The metabolite patterns obtained by TLC of extracts from serum and urine demonstrated that 17alpha-estradiol is the subject of a poor phase I metabolism in man. A great discrepancy was found in the serum concentrations of 17alpha-estradiol (free + conjugated) determined by GC/MS and the serum radioactivity expressed in 17alpha-estradiol equivalents. By TLC analysis of the steroid conjugates extracted from serum, various 17alpha-estradiol conjugate peaks were found. By enzymatic hydrolysis with beta-glucuronidase/aryl sulfatase from Helix pomatia they were only partially cleaved. Thus, the difference between the serum radioactivity and the 17alpha-estradiol levels determined by GC/MS had to be attributed to an incomplete conjugate hydrolysis. It has been shown with the synthesized 17alpha-estradiol sulfate conjugates that only the 3-sulfate is cleaved by enzymatic hydrolysis, whereas the 17-sulfate group resists enzymatic hydrolysis. The methanolysis procedure (acetyl chloride in MeOH) has proved to be an efficient method for cleaving both the 3-sulfate group and the 17-sulfate group. In contrast to the 17alpha-estradiol conjugates in serum, the urinary conjugates were intensively split by the enzyme preparation. From this, it has to be concluded that the serum conjugates were deconjugated and newly reconjugated before urinary excretion.     

Der Bau der Canini bei den Paulchoffatiidae (Multituberculata; Ober-Jura)

Canines are preserved among Multituberculata only in the upper jaw of the Paulchoffatiidae, the Pinheirodontidae and the North American genusGliodon Engelmann &; Callison, 1999. They resemble the anterior premolars (p^1–3) in the morphology of their crown, but they differ from them by the presence of only one root. In the present paper, 126 isolated canines of the Paulchoffatiidae from the Guimarota coal-pit in Portugal are treated. They show a wide morphological variation, from bicuspid to pentacuspid expression, and they can be grouped into 18 morphological units (Tab. 1). The bicuspid canines (11 specimens) show one buccal and one lingual cusp, arranged side by side, the latter normally being larger than the former. In the tricuspid canines (32 specimens) the cusps (one buccal and two lingual) are arranged in a triangle, with a great variation in the position of the cusps to each other. Tetracuspid canines (69 specimens) are the dominating group. Two buccal and two lingual cusps are present, which differ markedly in their largeness and their position to each other. The teeth differ also much in the shape of their crown. The pentacuspid canines (14 specimens) show two buccal and three lingual cusps. The variation in the arrangement of the cusps and in the shape of the crown is similar as in the tetracuspid specimens. One or two small cuspules can be present at the anterior border of the crown additionally to the main cusps in the canines. Tricuspid and tetracuspid canines are present also in the skulls of the Paulchoffatiidae, whereas bicuspid and pentacuspid canines are known only as isolated specimens. In the Pinheirodontidae the canines are tricuspid or tetracuspid, inGlirodon they are unicuspid. The Paulchoffatiidae and Pinheirodontidae — Paulchoffatiid line sensuKielan-Jaworowska &; Hurum, 2001 — are characterized by increasing premolarization of the upper canines. With that they differ markedly from all other multituberculates where the canini become reduced.     

Structure of tyrolobibenzyl D and biological activity of tyrolobibenzyls from Scorzonera humilis

A novel tyrolobibenzyl derivative, 1-->beta-D-apiosyl-beta-D-glucopyranosyl 4-[2-(4-hydroxyphenyl)ethyl]benzofuran-2-carboxylate 3 (tyrolobibenzyl D) was isolated from Scorzonera humilis L. and its structure established by mass spectrometry and 1D- and 2D-NMR spectroscopy. The biological activities of the new compound and related tyrolobibenzyls A-C (1-2, 4) and the semi-synthetic peracetyl derivatives of tyrolobibenzyls B (2a) and C (4a) were assessed. The results revealed no cytotoxic activity against P388 cells and neither anti-bacterial activity against Bacillus subtilis nor antifungal activity against Candida albicans and Trichophyton mentagrophytes for any of the investigated compounds. An evaluation of potential chemopreventive activity of 2, 2a, 4, and 4a also revealed no pronounced activity in any of the employed assaying systems.     

Culture of Echinococcus multilocularis metacestodes: an alternative to animal use

This article reviews the use of an in vitro culture model for the maintenance and proliferation of Echinococcus multilocularis metacestodes and the formation of protoscoleces. This model has been used to identify and characterize parasite molecules involved in host-parasite interactions, and is a suitable tool to perform in vitro drug-screening assays. The development of a simple and easy-to-handle assay to determine the effects of drugs on parasite viability, without the need for time-consuming animal experimentation, has opened the way for larger-scale in vitro drug screening.     

Differences in mRNA expression,protein content,and enzyme activity of superoxide dismutases in type II pneumocytes of acute and chronic lung injury

The lung is protected against oxidative stress by a variety of antioxidants and type II pneumocytes seem to play an important role in antioxidant defense. Previous studies have shown that inhalation of NO₂ results in acute and chronic lung injury. How the expression and enzyme activity of antioxidant enzymes are influenced in type II cells of different inflammatory stages has yet not been studied. To elucidate this question, we exposed rats to 10 ppm NO₂ for 3 or 20 days to induce acute or chronic lung injury. From these and air-breathing rats, type II pneumocytes were isolated. The mRNA expression and protein content of CuZnSOD and MnSOD as well as total SOD-specific enzyme activity were determined. For the acute lung injury (3 d NO₂), the expression of CuZnSOD mRNA was significantly increased, while MnSOD expression was significantly reduced after 3 days of NO 2 exposure. For the chronic lung injury (20 d NO₂), CuZnSOD expression was still enhanced, while MnSOD expression was comparable to control. In parallel to CuZnSOD mRNA expression, the protein amount was significantly increased in acute and chronic lung injury however MnSOD protein content exhibited no intergroup differences. Total SOD enzyme activity showed a significant decrease after 3 days of NO₂ exposure and was similar to control after 20 days. We conclude that during acute and chronic lung injury in type II pneumocytes expression and protein synthesis of CuZnSOD and MnSOD are regulated differently.     

Generation of carbon monoxide and iron from hemeproteins in the presence of 7,8-dihydroneopterin

7,8-Dihydroneopterin and neopterin are secreted by human and primate macrophages after activation by interferon-gamma in a ratio of 2:1. 7,8-Dihydroneopterin is known to suppress radical-mediated processes, but it is also able in the presence of iron ions to generate superoxide radical anion and hydroxyl radicals from molecular oxygen. Effects of 7,8-dihydroneopterin were investigated on (met)myoglobin and (met)hemoglobin. Addition of 7,8-dihydroneopterin to heme proteins in air-saturated solution resulted in dose-dependent cleavage of the porphyrin moiety. The liberation of non-heme iron and carbon monoxide originating from the cleaved porphyrin was quantified. Both were generated at equimolar concentrations with a linear correlation coefficient of 0.9. Addition of ferrous iron significantly accelerated the pteridine-mediated cleaving of the porphyrin. However, the total yield of porphyrin cleaved was controlled by the pterin rather than by the ferrous ion concentration. 7,8-Dihydroneopterin is assumed to reduce the heme iron in intact protein molecules, thereby preparing the conditions for binding of oxygen and carbon monoxide as ligands. Beyond that, it is concluded that hydroxyl radicals might be generated via reduction of molecular oxygen to superoxide anion in the autoxidation process and dismutation to hydrogen peroxide and subsequent Fenton reaction.