The use of stable isotopes to trace small-scale movements by small fish species

Valuable biological information can be obtained by monitoring the movement of organisms. However, the choice of monitoring method becomes highly restricted when following small organisms (<100 mm), especially in aquatic ecosystems. Stable isotopes are being increasingly used in this respect but rarely at the local spatial scale, i.e. 10–1000 s of metres. We sought to identify movement of small fishes between a main river channel and its tributary. Little overlap in isotope baseline was detected between the two channels despite some temporal variability in δ¹⁵N of baseline indicator organisms in the main river. The individuals of two small cyprinid fish species (Leuciscus souffia and Alburnoides bipunctatus) of all the size classes (40–100 mm) caught within the tributary showed considerable heterogeneity in δ¹⁵N values. Classification and discriminant analysis on isotope-derived data distinguished two significantly different groups. Moreover, this result was supported by further sampling of fish caught in the main river (in May and December 2006). Alternative hypotheses, such as dietary differences, biological factors, temporal shifts and spatial differences in diet, did not explain δ¹⁵N variability. This application of stable isotopes at a relatively small spatial and temporal scales further demonstrates its potential as a tool for ecologists.     

In vivo neutralization of TNF-alpha promotes humoral autoimmunity by preventing the induction of CTL.

Neutralization of TNF-alpha in humans with rheumatoid arthritis or Crohn's disease has been associated with the development of humoral autoimmunity. To determine the effect of TNF-alpha neutralization on cell-mediated and humoral-mediated responses, we administered anti-TNF-alpha mAb to mice undergoing acute graft-vs-host disease (GVHD) using the parent-into-F(1) model. In vivo neutralization of TNF-alpha blocked the lymphocytopenic features characteristic of acute GVHD and induced a lupus-like chronic GVHD phenotype (lymphoproliferation and autoantibody production). These effects resulted from complete inhibition of detectable antihost CTL activity and required the presence of anti-TNF-alpha mAb for the first 4 days after parental cell transfer, indicating that TNF-alpha plays a critical role in the induction of CTL. Moreover, an in vivo blockade of TNF-alpha preferentially inhibited the production of IFN-gamma and blocked IFN-gamma-dependent up-regulation of Fas; however, cytokines such as IL-10, IL-6, or IL-4 were not inhibited. These results suggest that a therapeutic TNF-alpha blockade may promote humoral autoimmunity by selectively inhibiting the induction of a CTL response that would normally suppress autoreactive B cells.     

Biochemical Conservation and Evolution of Germacrene A Oxidase in Asteraceae

Sesquiterpene lactones are characteristic natural products in Asteraceae, which constitutes ∼8% of all plant species. Despite their physiological and pharmaceutical importance, the biochemistry and evolution of sesquiterpene lactones remain unexplored. Here we show that germacrene A oxidase (GAO), evolutionarily conserved in all major subfamilies of Asteraceae, catalyzes three consecutive oxidations of germacrene A to yield germacrene A acid. Furthermore, it is also capable of oxidizing non-natural substrate amorphadiene. Co-expression of lettuce GAO with germacrene synthase in engineered yeast synthesized aberrant products, costic acids and ilicic acid, in an acidic condition. However, cultivation in a neutral condition allowed the de novo synthesis of a single novel compound that was identified as germacrene A acid by gas and liquid chromatography and NMR analyses. To trace the evolutionary lineage of GAO in Asteraceae, homologous genes were further isolated from the representative species of three major subfamilies of Asteraceae (sunflower, chicory, and costus from Asteroideae, Cichorioideae, and Carduoideae, respectively) and also from the phylogenetically basal species, Barnadesia spinosa, from Barnadesioideae. The recombinant GAOs from these genes clearly showed germacrene A oxidase activities, suggesting that GAO activity is widely conserved in Asteraceae including the basal lineage. All GAOs could catalyze the three-step oxidation of non-natural substrate amorphadiene to artemisinic acid, whereas amorphadiene oxidase diverged from GAO displayed negligible activity for germacrene A oxidation. The observed amorphadiene oxidase activity in GAOs suggests that the catalytic plasticity is embedded in ancestral GAO enzymes that may contribute to the chemical and catalytic diversity in nature.     

Changes in plasma electrolytes and their regulatory hormones during an acute exposure to heat. Human studies in a Finnish sauna

Plasma Na, K, Cl, Ca, P didn't or moderately be altered by exposure to acute heat in sauna bath (20 mn, 80 degrees C, relative humidity 15-20%). However, CO2T decreased, ARP, aldosterone, ACTH, PRL increased, and PTH wasn't modified.     

RNA editing of 10 Didymium iridis mitochondrial genes and comparison with the homologous genes in Physarum polycephalum

Regions of the Didymium iridis mitochondrial genome were identified with similarity to typical mitochondrial genes; however, these regions contained numerous stop codons. We used RT-PCR and DNA sequencing to determine whether, through RNA editing, these regions were transcribed into mRNAs that could encode functional proteins. Ten putative gene regions were examined: atp1, atp6, atp8, atp9, cox1, cox2, cytb, nad4L, nad6, and nad7. The cDNA sequences of each gene could encode a functional mitochondrial protein that was highly conserved compared with homologous genes. The type of editing events and editing sequence features were very similar to those observed in the homologous genes of Physarum polycephalum, though the actual editing locations showed a variable degree of conservation. Edited sites were compared with encoded sites in D. iridis and P. polycephalum for all 10 genes. Edited sequence for a portion of the cox1 gene was available for six myxomycetes, which, when compared, showed a high degree of conservation at the protein level. Different types of editing events showed varying degrees of site conservation with C-to-U base changes being the least conserved. Several aspects of single C insertion editing events led to the preferential creation of hydrophobic amino acid codons that may help to minimize adverse effects on the resulting protein structure.     

Synthesis and biological activity of linear and cyclic enkephalins modified at the Gly3-Phe4 amide bond

As part of our continuing effort to define structure-activity relationships for enkephalin and design enzymatically resistant analogs, we report the synthesis and biological activities of linear and cyclic enkephalin analogs modified at the Gly3-Phe4 amide bond. The partial retro-inverso enkephalin analog Tyr-D-Ala-gGly-(R,S)-mPhe-Leu-NH2 and its cyclic counterpart, Tyr-cyclo[D-A2 bu-gGly-(R,S)-mPhe-Leu-], were synthesized as diastereomeric mixtures using solution methodology. The racemic benzylmalonate allowed the linear analog to be synthesized by fragment coupling at the reversed bond. Cyclization of the second analog was carried out at high concentration, eliminating formation of polymer by the use of an insoluble base. All gem-diaminoalkyl residues were prepared by conversion of peptidyl amides with benzene iodonium bis(trifluoroacetate). Diastereomers of both compounds were separable by reverse phase HPLC but those of the linear compound racemized rapidly under conditions of testing and were therefore tested together. All analogs tested had activities ranging from 6 to 14% of the activity of Leu enkephalin, indicating that the Gly3-Phe4 amide bond is important, though not crucial, for receptor binding.     

Effect of Phosphate on the Corrosion of Carbon Steel and on the Composition of Corrosion Products in Two-Stage Continuous Cultures of Desulfovibrio desulfuricans

A field isolate of Desulfovibrio desulfuricans was grown in defined medium in a two-stage continuous culture apparatus with different concentrations of phosphate in the feed medium. The first state (V1) was operated as a conventional chemostat (D = 0.045 h⁻¹) that was limited in energy source (lactate) or phosphate. The second stage (V2) received effluent from V1 but no additional nutrients, and contained a healthy population of transiently starved or resting cells. An increase in the concentration of phosphate in the medium fed to V1 resulted in increased corrosion rates of carbon steel in both V1 and V2. Despite the more rapid corrosion observed in growing cultures relative to that in resting cultures, corrosion products that were isolated under strictly anaerobic conditions from the two culture modes had similar bulk compositions which varied with the phosphate content of the medium. Crystalline mackinawite (Fe₉S₈), vivianite [Fe₃(PO₄)₂ · 8H₂O], and goethite [FeO(OH)] were detected in amounts which varied with the culture conditions. Chemical analyses indicated that the S in the corrosion product was almost exclusively in the form of sulfides, while the P was present both as phosphate and as unidentified components, possibly reduced P species. Some differential localization of S and P was observed in intact corrosion products. Cells from lactate-limited, but not from phosphate-limited, cultures contained intracellular granules that were enriched in P and Fe. The results are discussed in terms of several proposed mechanisms of microbiologically influenced corrosion.     

The recovery of normal DNA replication kinetics in ultraviolet-irradiated Chinese hamster cells

The kinetics of DNA replication were analyzed in the second S phase following UV irradiation of Chinese hamster ovary cells synchronized at the beginning of S phase. The cells were synchronized by treating cells selected in mitosis with hydroxyurea for 9 h. Following UV irradiation, the cells were allowed to progress until the next mitosis; at which time they were resynchronized at the beginning of the second S phase by the same procedure. The kinetics of DNA replication were determined by measuring the proportion of DNA which achieved hybrid buoyant density on CsCl density gradients as a function of the time of incubation in the presence of 5-bromodeoxyuridine.The results of these experiments showed that even though the rate of DNA replication is substantially depressed during the first S phase following UV irradiation with a fluence of 5 J/m², the rate has recovered to the extent that it is indistinguishable from the unirradiated control by the time the cells have entered their second S phase. It was concluded from these observations that the lesions in DNA which caused the rate of DNA replication to be initially depressed during the first S phase have been either removed or modified such that they no longer are able to cause a reduction in the rate of DNA replication in the second S phase following UV irradiation.