In vitro regeneration of Gaillardia pulchella Foug.

Young leaf and internodal stem segments of Gaillardia pulchella, collected from wild species re-established in the greenhouse, were used to initiate callus on Murashige & Skoog medium supplemented with NAA (2.0 mgl⁻¹) and BA (0.4 mgl⁻¹). Callus formed after 10 to 14 days in the dark. Cultures were transferred to fresh medium and placed under lighted conditions where shoot formation occurred approximately 14 to 30 days after initiation. Callus sub-cultured at 14 to 21-day intervals continued to produce primordia for several weeks. Flowers were produced by regenerated shoots maintained on MS medium, but roots did not develop until the plantlets were transferred to soil conditions.     

Evaluation of D1 and D2 Dopamine Receptor Segregation in the Developing Striatum Using BAC Transgenic Mice

The striatum is predominantly composed of medium spiny neurons (MSNs) that send their axons along two parallel pathways known as the direct and indirect pathways. MSNs from the direct pathway express high levels of D1 dopamine receptors, while MSNs from the indirect pathway express high levels of D2 dopamine receptors. There has been much debate over the extent of colocalization of these two major dopamine receptors in MSNs of adult animals. In addition, the ontogeny of the segregation process has never been investigated. In this paper, we crossed bacterial artificial chromosome drd1a-tdTomato and drd2-GFP reporter transgenic mice to characterize these models and estimate D1-D2 co-expression in the developing striatum as well as in striatal primary cultures. We show that segregation is already extensive at E18 and that the degree of co-expression further decreases at P0 and P14. Finally, we also demonstrate that cultured MSNs maintain their very high degree of D1-D2 reporter protein segregation, thus validating them as a relevant in vitro model.     

Using fish guilds to assess community responses to temperature and flow regimes in unregulated and regulated Canadian rivers

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Methane production in an UASB reactor operated under periodic mesophilic-thermophilic conditions

Methane production was studied in a laboratory-scale 10 L anaerobic upflow sludge bed (UASB) reactor with periodic variations of the reactor temperature. On a daily basis the temperature was varied between 35 and 45 degrees C or 35 and 55 degrees C with a heating period of 6 h. Each temperature increase was accompanied by an increase in methane production and a decrease in the concentration of soluble organic matter in the effluent. In comparison to a reactor operated at 35 degrees C, a net increase in methane production of up to 22% was observed. Batch activity tests demonstrated a tolerance of mesophilic methanogenic populations to short-term, 2-6 h, temperature increases, although activity of acetoclastic methanogens decreased after 6 h exposure to a temperature of 55 degrees C. 16S sequencing of DGGE bands revealed proliferation of temperature-tolerant Methanospirillum hungatii sp. in the reactor.     

Canopy photosynthesis modulates soil respiration in a temperate semi-arid shrubland at multiple timescales

Plant and Soil - Plant growth-promoting bacteria of the genus Bacillus are known to solubilize phosphates and enhance plant growth in many plant species. We explored the effects of the inoculation...     

Detailed four-way comparative mapping and gene order analysis of the canine ctvm locus reveals evolutionary chromosome rearrangements

Canine tricuspid valve malformation (CTVM) maps to canine chromosome 9 (CFA9), in a region syntenic with gene-dense human chromosome 17q. To define synteny blocks, we analyzed 148 markers on CFA9 using radiation hybrid mapping and established a four-way comparative map for human, mouse, rat, and dog. We identified a large number of rearrangements, allowing us to reconstruct the evolutionary history of individual synteny blocks and large chromosomal segments. A most parsimonious rearrangement scenario for all four species reveals that human chromosome 17q differs from CFA9 and the syntenic rodent chromosomes through two macroreversals of 9.2 and 23 Mb. Compared to a recovered ancestral gene order, CFA9 has undergone 11 reversals of <3 Mb and 2 reversals of >3 Mb. Interspecies reuse of breakpoints for micro- and macrorearrangements was observed. Gene order and content of the ctvm interval are best extrapolated from murine data, showing that multispecies genome rearrangement scenarios contribute to identifying gene content in canine mapping studies.     

High-cell-density production of poly-β-hydroxybutyrate (PHB) from methanol by Methylobacterium extorquens: production of high-molecular-mass PHB

Methylobacterium extorquens ATCC 55366 was successfully cultivated at very high cell densities in a fed-batch fermentation system using methanol as a sole carbon and energy source and a completely minimal culture medium for the production of poly--hydroxybutyrate (PHB). Cell biomass levels were between 100 g/l and 115 g/l (dry weight) and cells contained between 40% and 46% PHB on a dry-weight basis. PHB with higher molecular mass values than previously reported for methylotrophic bacteria was obtained under certain conditions. Shake-flask and fermentor experiments showed the importance of adjusting the mineral composition of the medium for improved biomass production and higher growth rates. High-cell-density cultures were obtained without the need for oxygen-enriched air; once the oxygen transfer capacity of the fermentor was reached, methanol was thereafter added in proportion to the amount of available dissolved oxygen, thus preventing oxygen limitation. Controlling the methanol concentration at a very low level (less than 0.01 g/l), during the PHB production phase, led not only to prevention of oxygen limitation but also to the production of very high-molecular-mass PHB, in the 900–1800 kDa range. Biomass yields relative to the total methanol consumed were in the range 0.29–0.33 g/g, whereas PHB yields were in the range 0.09–0.12 g/g. During the active period of PHB synthesis, PHB yields relative to the total methanol consumed were between 0.2 g/g and 0.22 g/g. M. extorquens ATCC 55366 appears to be a promising organism for industrial PHB production.