Localization of carbohydrate components in rat colon with fluoresceinated lectins

Cryostat sections of rat descending colon were studied by fluorescence microscopy after exposure to conjugates of fluorescein isothicoyanate with lectins from Glycine max (soybean), Triticum vulgaris (wheat germ), Ricinus communis (castor bean), Ulex europaeus, (gorse), Dolichos biflorus (horse gram) and Canavalia ensiformis (concanavalin A) (Jack bean). No two lectins showed identical patterns of fluorescence. FITC-conjugates of soybean and D. biflorus lectins reacted strongly with the mucus present in the crypt lumens and with the surface (as well as cytoplasm) of the epithelial cells suggesting that these sites are rich in terminal, non-reducing, N-acetylgalactosamine residues. Wheat germ, R. communis, U. europaeus and concanavalin A-FITC conjugates did not stain mucus but showed fluorescence in the cytoplasm of absorptive cells as well as in the lamina propria and submucosa. The FITC-R. communis conjugate also reacted with structures in the apical portion of epithelial cells that may correspond to the Golgi apparatus.     

The role of voltage-gated Ca2+ channels in neurite growth of cultured chromaffin cells induced by extremely low frequency (ELF) magnetic field stimulation

The ion Ca²⁺ has been shown to play an important role in a wide variety of cellular functions, one of them being related to cell differentiation in which nerve growth factor (NGF) is involved. Chromaffin cells obtained from adrenals of 2- to 3-day-old rats were cultured for 7 days. During this time, these cells were subjected to the application of either NGF or extremely low frequency magnetic fields (ELF MF). Since this induced cell differentiation toward neuronal-like cells, the mechanism by which this occurred was studied. When the L-Ca²⁺ channel blocker nifedipine was applied simultaneously with ELF MF, this differentiation did not take place, but it did when an N-Ca²⁺ channel blocker was used. In contrast, none of the Ca²⁺ channel blockers prevented differentiation in the presence of NGF. In addition, Bay K-8644, an L-Ca²⁺ channel agonist, increased both the percentage of differentiated cells and neurite length in the presence of ELF MF. This effect was much weaker in the presence of NGF. [³H]-noradrenaline release was reduced by nifedipine, suggesting an important role for L-Ca²⁺ channels in neurotransmitter release. Total high voltage Ca²⁺ currents were significantly increased in ELF MF-treated cells with NGF, but these currents in ELF MF-treated cells were more sensitive to nifedipine. Amperometric analysis of catecholamine release revealed that the KCl-induced activity of cells stimulated to differentiate by ELF MF is highly sensitive to L-type Ca²⁺ channel blockers. A possible mechanism to explain the way in which the application of magnetic fields can induce differentation of chromaffin cells into neuronal-like cells is proposed.     

Gas permeable deep reaching fracture zones encourage site selection of ants

Difficulties with geological mapping of fault patterns occur frequently due to missing outcrops and typically fault mineralization (e.g. crystalline quartz and ore mineralization). Alternatively, in addition to other analyses, soil gas measurements (e.g. helium) can be carried out. Due to fault zone complexity, geologists must often rely on other, in some cases, easier indications of their existence. Geological studies in several areas of central Europe especially in the Middle Rhine Region (Rhenish Massif) indicate that active gas permeable fracture zones are linked to linear distributions of nests of hill-building forest ants. Therefore, the possibility of using formicines as indicators of gas permeable fault patterns was investigated. These preliminary data indicated the possible interaction of site selection and active gas permeable fracture zones. Consequently, regions in the Alps, the Black Forest, the Lower Rhine Embayment, Bavaria, Hesse and South Sweden were chosen, ant nests were mapped, and their sites subsequently compared to geological structures. Most of the investigated ant nests were located on or near active gas permeable faults. Additionally, in the Middle Rhine Region variations in population size of formicines on fault zones and inter fault zones have been observed. These primary data suggest formicines can be applied successfully as an aid to fault pattern location.     

Degratation of 3-hydroxyflavone by horse radish peroxidase

A hydroxylic group in position 3 and a double bond between positions 2 and 3 is the minimum requirement for flavones to be substrates for horse radish peroxidase (EC 1.11.1.7). 3-Hydroxyflavone, fulfilling these requirements, yields on enzymatic cleavage salicylic, phenylglyoxylic and probably benzoic acid.     

Patterns of richness and endemism of the Mexican herpetofauna,a matter of spatial scale?

The goal of this study was to compare the richness and endemism patterns of Mexican species of amphibians and reptiles at different spatial scales. We used the best available dataset of distributional ranges generated from ecological niche models and employed geographically weighted regressions (GWRs) to test whether richness and endemism were related. Patterns were found to vary with the scale used for richness and endemism, and these patterns were not coincident. The results showed that: (1) only relatively coarse spatial scales can address latitudinal patterns in amphibians and reptiles, and, in fine scales, they are related to topographic formations; (2) areas of greatest endemism for amphibians and reptiles are located in the highlands of the central or southern part of the country, although not necessarily in the same specific highlands for both groups; (3) there is a strong average correlation between richness and endemism for both groups, indicating that the same factors contribute to both patterns, but these factors act differentially in terms of regions among amphibians and reptiles; and (4) the scale at which the analysis is conducted is important, and we believe that careful consideration of spatial scale must be undertaken to avoid false conclusions. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 305–316.     

The Bidirectional NiFe-hydrogenase in Synechocystis sp. PCC 6803 Is Reduced by Flavodoxin and Ferredoxin and Is Essential under Mixotrophic,Nitrate-limiting Conditions

Cyanobacteria are able to use solar energy for the production of hydrogen. It is generally accepted that cyanobacterial NiFe-hydrogenases are reduced by NAD(P)H. This is in conflict with thermodynamic considerations, as the midpoint potentials of NAD(P)H do not suffice to support the measured hydrogen production under physiological conditions. We show that flavodoxin and ferredoxin directly reduce the bidirectional NiFe-hydrogenase of Synechocystis sp. PCC 6803 in vitro. A merodiploid ferredoxin-NADP reductase mutant produced correspondingly more photohydrogen. We furthermore found that the hydrogenase receives its electrons via pyruvate:flavodoxin/ferredoxin oxidoreductase (PFOR)-flavodoxin/ferredoxin under fermentative conditions, enabling the cells to gain ATP. These results strongly support that the bidirectional NiFe-hydrogenases in cyanobacteria function as electron sinks for low potential electrons from photosystem I and as a redox balancing device under fermentative conditions. However, the selective advantage of this enzyme is not known. No strong phenotype of mutants lacking the hydrogenase has been found. Because bidirectional hydrogenases are widespread in aquatic nutrient-rich environments that are capable of triggering phytoplankton blooms, we mimicked those conditions by growing cells in the presence of increased amounts of dissolved organic carbon and dissolved organic nitrogen. Under these conditions the hydrogenase was found to be essential. As these conditions close the two most important sinks for reduced flavodoxin/ferredoxin (CO₂-fixation and nitrate reduction), this discovery further substantiates the connection between flavodoxin/ferredoxin and the NiFe-hydrogenase.