Lathyrane type diterpene esters from Euphorbia lathyris

By reversed phase HPLC ‘ester L₇’, previously isolated among several macrocyclic lathyrol derivatives from seeds of Euphorbia lathyris, was     

CorrXpression--identification of significant groups of genes and experiments by means of correspondence analysis and ratio analysis

CorrXpression is a stand-alone desktop application for the identification of significant genes within collections of microarrays. The software combines three methods in two steps of analysis: correspondence analysis (CA), ratio analysis and correlation analysis. The graphical interface of CorrXpression visualizes the result of the CA with a biplot and the expression of selected genes in dependency of the experiments as bar diagrams. The CA-plot is an excellent tool for visualization and evaluation of data and results of ratio analysis and correlation analysis. The input data are selected from a database or from appropriate ASCII files.     

Molecular dynamics simulation of dextran extension by constant force in single molecule AFM

The extension of 1-6 polysaccharides has been studied in a series of recent single molecule AFM experiments. For dextran, a key finding was the existence of a plateau in the force-extension curve at forces between 700 and 1000 pN. We studied the extension of the dextran 10-mer under constant force using atomistic simulation with various force fields. All the force fields reproduce the experimental plateau on the force-extension curve. With AMBER94 and AMBER-GLYCAM04 force fields the plateau can be explained by a transition of the glucopyranose rings in the dextran monomers from the chair ((4)C(1)) to the inverted chair ((1)C(4)) conformation while other processes occur at smaller (rotation around C5-C6 bond) or higher (chairs to boat transitions) forces. The CHARMM force field provides a different picture which associates the occurrence of the plateau to chair-boat transitions of the glucopyranose rings.     

Modulation of polyunsaturated fatty acids in mixotrophic Karlodinium veneficum (Dinophyceae) and its prey,Storeatula major (Cryptophyceae)1

We examined whether fatty acid (FA) composition changed when Karlodinium veneficum (D. Ballantine) J. Larsen (Dinophyceae) was grown phototrophically or mixotrophically on Storeatula major Butcher ex D. R. A. Hill (Cryptophyceae). We hypothesized that the FA composition of mixotrophic K. veneficum would not change relative to the FA composition of phototrophic K. veneficum. As in other phototrophic dinoflagellates, octadecapentaenoic acid (18:5n3) represented 9% to 20% of total FA in K. veneficum and was enriched within chloroplast‐associated galactolipid classes. The 18:5n3 content showed a highly significant positive correlation (r² = 0.95) with chl a content and a highly significant negative correlation with growth rate (r² = 0.88). A previously undescribed chloroplast galactolipid molecular species, digalactosyldiacylglycerol (DGDG; 18:5n3/18:5n3), was a dominant structural lipid in K. veneficum. Docosahexaenoic acid (22:6n3) represented 14% to 19% of total K. veneficum FA and was enriched within phospholipids. In the prey S. major, 18:5n3 was not present, but octadecatetraenoic acid (18:4n3) and α‐linolenic acid (18:3n3) represented approximately 50% of total FA and were enriched within chloroplast‐associated galactolipid classes. Eicosapentaenoic acid (20:5n3) and 22:6n3 represented approximately 18% of total FA in S. major and were enriched within phospholipids. The FA profile of mixotrophic K. veneficum, compared to phototrophic K. veneficum, showed elevated levels of 18:3n3, 18:4n3, and 20:5n3, and lower but persistent levels of 18:5n3. Production to ingestion (P:I) ratios >1 for major polyunsaturated fatty acids (PUFAs) indicated that direct assimilation from prey under balanced growth could not support rates of PUFA production in mixotrophic K. veneficum. These data suggest that the plastid plays a continuing and essential role in lipid metabolism during mixotrophic growth.     

Rhizobium halotolerans sp. nov., Isolated from Chloroethylenes Contaminated Soil

The strain designated as AB21^T was isolated from chloroethylenes contaminated soil. Cells are gram-negative, aerobic, non-spore-forming, and motile rods. Phylogenetic analysis based on 16S rRNA gene sequence showed that it belonged to the genus Rhizobium, and was closely related to Rhizobium sullae IS 123^T (97.4 %), Rhizobium yanglingense SH 22623^T (97.2 %), Rhizobium gallicum R 602sp^T (97.1 %), Rhizobium alamii GBV 016^T (97.0 %), and Rhizobium monogolense USDA 1844^T (97.0 %). It showed less than 97 % identity with the remaining Rhizobium species. This novel isolate grew optimally at 25–37 °C (optimum, 30 °C) and pH 6–9 (optimum, pH 8.0). It grew in the presence of 0–4 % (w/v) NaCl, tolerating a 4 % (w/v) NaCl. DNA–DNA hybridization experiment shows less than 53 % binding with closely related Rhizobium. Predominant quinone is ubiquinone (Q-10). The major fatty acids were summed feature 8 (composed of C_18:1 ω7c/C_18:1 ω6c), C_19:0 cyclo ω8c, and C_16:0. The G+C molar content is 62.5 mol%. Based on the polyphasic analysis, strain AB21^T is referred to be a novel species of the genus Rhizobium for which the name Rhizobium halotolerans sp. nov. is proposed. The type strain is AB21^T (=KEMC 224-056^T = JCM 17536^T).     

A Frequent PNPLA3 Variant Is a Sex Specific Disease Modifier in PSC Patients with Bile Duct Stenosis

Background & Aims

Primary sclerosing cholangitis predominantly affects males and is an important indication for liver transplantation. The rs738409 variant (I148M) of the PNPLA3 gene is associated with alcoholic and non-alcoholic liver disease and we evaluated its impact on the disease course of PSC.

Methods

The I148M polymorphism was genotyped in 121 German PSC patients of a long-term prospective cohort and 347 Norwegian PSC patients.

Results

In the prospective German cohort, actuarial survival free of liver transplantation was significantly reduced for I148M carriers (p = 0.011) compared to wildtype patients. This effect was restricted to patients with severe disease, as defined by development of dominant stenosis (DS) requiring endoscopic intervention. DS patients showed markedly decreased survival (p = 0.004) when carrying the I148M variant (I148M: mean 13.8 years; 95% confidence interval: 11.6–16.0 vs. wildtype: mean 18.6 years; 95% confidence interval: 16.3–20.9) while there was no impact on survival in patients without a DS (p = 0.87). In line with previous observations of sex specific effects of the I148M polymorphism, the effect on survival was further restricted to male patients (mean survival 11.9 years; 95% confidence interval: 10.0–14.0 in I148M carriers vs. 18.8 years; 95% confidence interval: 16.2–21.5 in wildtype; p<0.001) while female patients were unaffected by the polymorphism (p = 0.65). These sex specific findings were validated in the Norwegian cohort (p = 0.013).

Conclusions

In male PSC patients with severe disease with bile duct stenosis requiring intervention, the common I148M variant of the PNPLA3 gene is a risk factor for reduced survival.     

Acid–base regulation in isolated gill cells of the goldfish (Carassius auratus)

Mechanisms of acid release and intracellular pH (pH_i) homeostasis were analysed in goldfish (Carassius auratus) gill cells in primary culture. The rate of acid secretion was measured using a cytosensor microphysiometer, and pH_i was determined using the fluorescent probe 2,7-bis-(3-carboxypropyl)-5-(and-6)-carboxyfluorescein (BCPCF). Amiloride, a Na⁺ channel and Na⁺/H⁺ exchanger (NHE) inhibitor, had no effect on pH_i, but acid secretion of the gill cells was significantly impaired. In the presence of amiloride, the intracellular acidification (achieved using the NH₄Cl pulse technique) was more severe than in the absence of amiloride, and recovery from the acidosis was slowed down. Accordingly, acid secretion of gill cells was severely reduced in the absence of extracellular Na⁺. Under steady-state conditions, 4,4-diisothiocyanatodihydro-stilbene-2,2-disulfonic acid (DIDS), a HCO₃^–-transport inhibitor, caused a slow acidification of pH_i, and acid secretion was significantly reduced. No recovery from intracellular acidification was observed in the presence of DIDS. Bafilomycin A₁, an inhibitor of V-ATPase, had no effect on steady-state pH_i and recovery from an intracellular acidification, whereas the rate of acid secretion under steady-state conditions was slightly reduced. Immunohistochemistry clearly revealed the presence of the V-ATPase B-subunit in goldfish gill lamellae. Taken together, these results suggest that a Na⁺-dependent HCO₃^– transport is the dominant mechanism besides an NHE and V-ATPase to control pH_i in goldfish gill cells.Communicated by G. Heldmaier     

AUTOTROPHIC GROWTH AND PHOTOACCLIMATION IN KARLODINIUM MICRUM (DINOPHYCEAE) AND STOREATULA MAJOR (CRYPTOPHYCEAE)1

We compared autotrophic growth of the dinoflagellate Karlodinium micrum (Leadbeater et Dodge) and the cryptophyte Storeatula major (Butcher ex Hill) at a range of growth irradiances (E_g). Our goal was to determine the physiological bases for differences in growth–irradiance relationships between these species. Maximum autotrophic growth rates of K. micrum and S. major were 0.5 and 1.5 div.·d^?1, respectively. Growth rates were positively correlated with C‐specific photosynthetic performance (PP^C, g C·g C^?1·h^?1) (r²=0.72). Cultures were grouped as light‐limited (LL) and high‐light (HL) treatments to allow interspecific comparisons of physiological properties that underlie the growth–irradiance relationships. Interspecific differences in the C‐specific light absorption rate (E_a^C, mol photons·g C^?1·h^?1) were observed only among HL acclimated cultures, and the realized quantum yield of C fixation (φ_C(real.), mol C·mol photons^?1) did not differ significantly between species in either LL or HL treatments. The proportion of fixed C that was incorporated into new biomass was lower in K. micrum than S. major at each E_g, reflecting lower growth efficiency in K. micrum. Photoacclimation to HL in K. micrum involved a significant loss of cellular photosynthetic capacity (P_max^cell), whereas in S. major, P_max^cell was significantly higher in HL acclimated cells. We conclude that growth rate differences between K. micrum and S. major under LL conditions relate primarily to cell metabolism processes (i.e. growth efficiency) and that reduced chloroplast function, reflected in PP^C and photosynthesis–irradiance curve acclimation in K. micrum, is also important under HL conditions.     

Winter aspects of the ichthyoplankton community in Antarctic Peninsula waters

Summary Ichthyoplankton was sampled from the Antarctic Peninsula area of the South Polar Ocean in early winter (May and June 1986). A total of 153 eggs from two species and 1368 larvae or juvenile stages from 12 species were obtained. These included pelagic species, and demersal species with a long pelagic larval or juvenile phase. Most abundant were larvae of Pleuragramma antarcticum and Notothenia kempi, and eggs of Notothenia neglecta. The distribution of notothenioid and paralepidid larvae was apparently unaffected by ice cover, whereas myctophid larvae were confined to ice-free waters. Areas where newly hatched Chionodraco hamatus occurred coincided with dense aggregations of Euphausia superba (Krill) furcilia larvae which is a potential food resource during winter. The hatching of icefish larvae during winter is apparently independent of the seasonal production cycle. Epipelagic eggs of Notothenia neglecta were found during the spawning season, which suggests that eggs ascend to the surface after demersal spawning and that development takes place near the sea surface during winter. Larvae of Notothenia kempi were chiefly confined to shelf and slope waters to the west of the Antarctic Peninsula, with larger larvae found in coastal shelf areas. Pleuragramma antarcticum occurred in the coastal waters off the Biscoe Islands, in the Gerlache Strait, and in the northern Bransfield Strait. The smallest larvae were found in the northern Bransfield Strait, whereas those at the Biscoe Islands and in Gerlache Strait waters were larger and of a similar size. A cyclonic gyre to the west of the Antarctic Peninsula observed in the austral summer was likely to have affected the larval drift of Pleuragramma antarcticum and Notothenia kempi. Differences in the timing of spawning and hatching and the vertical distribution of these larvae will lead to different transport and spatial distribution patterns. It is hypothesized that early winter conditions do not imply severe limitations on the year-class success of larval fish. Dispersal and increased mortality may occur during the second half of the winter.