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Notes: Rutilus alburnoides complex is a common and widely distributed Iberian cyprinid, whose natural populations include mainly diploid and triploid forms. The Guadiana populations of R. alburnoides were studied to determine whether habitat segregation and morphological differences exist between these forms. The ploidy level of each specimen was determined by measuring erythrocyte DNA content using flow cytometry. Evidence of spatial segregation between diploid males and the two female forms was found. Diploid males were best represented in the River Degebe, which was shallow, with higher temperatures (especially during the spring and summer), and silt and sandy substrate. Diploid females were found in deeper water, on steeper gradients and coarse substrata, while triploid females preferred higher current velocity and a high proportion of instream cover, especially during the spring. The ecological differences may reduce competitive interactions, and should promote a stable coexistence of the different forms. Morphological distinction between fish of different ploidy levels was not established, but differences were found between the males and females. Discriminant analysis allowed, with a 10% error, the separation of both sexes through six morphological characteristics that could be recorded in the field.

Notes: Abstract Anaerobic treatment of distillery wastewaters containing high sulfate concentrations was carried out on a two-phase process. The acidogenic phase was operated so as to produce the more favourable intermediates for methanogenic bacteria coupled with maximum sulfate removal. Sulfate removal was directly affected by pH and dilution rate (D). The maximum sulfate removal and acetic acid production was achieved at pH 6.6 and D=0.035 h−1. A linear relationship between acetic acid produced and sulfate removal was observed, indicating that acetic acid was mainly produced by sulfate reducing bacteria with important operational advantages. Higher concentrations of butyric acid were obtained at low pH values and high dilution rates.

Notes: Abstract  1-Methyl-4-phenylpyridinium (MPP+), the neurotoxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), is efficiently taken up and accumulated by rat hepatocytes. However, the nature of the mechanism(s) involved in the hepatic uptake of MPP+ remains partially unknown. The aim of the present study was to further characterize the hepatic uptake of 3H-MPP+, namely by investigating the interactions of catecholamines (which are also efficiently taken up by rat hepatocytes) with MPP+ transport. The accumulation of 3H-MPP+ in isolated rat hepatocytes occurred through saturable and non-saturable mechanisms. The kinetics of the saturable component of 3H-MPP+ uptake was as follows: Vmax= 181.3±11.1 pmol mg protein-1 min-1 and Km= 47.1 μM (27.9, 66.3) (n=5). The diffusion constant (in ml mg protein-1 min-1) for the non-saturable uptake of 3H-MPP+ was 0.00068 (0.00052, 0.00083) (n=5). From the analysis of the time course of 3H-MPP+ accumulation at a substrate concentration of 100 nM 3H-MPP+, it was found that the rate constant of inward transport of 3H-MPP+ into hepatocytes (kin) was 15.7±3.8 μl mg protein-1 min-1, the rate constant of outward transport of 3H-MPP+ from hepatocytes (kout) was 0.077± 0.023 min-1 and the equilibrium accumulation (Amax) of 3H-MPP+ was 20.2±2.0 pmol mg protein-1 (n=36). Decynium22 (1,1′-diethyl-2,2′-cyanide; 1 μM) significantly reduced kin to 6.1±1.8 μl mg protein-1 min-1 (P〈0.05) and the equilibrium accumulation (Amax) of 3H-MPP+ to 9.6±1.3 pmol mg protein-1 (P〈0.005) (n=36). 3H-MPP+ accumulation (in cells incubated with 200 nM 3H-MPP+) was sensitive to (−)-adrenaline, (−)-isoprenaline, (−)-dopamine, (±)-adrenaline and (−)-noradrenaline. The most potent catecholamine in inhibiting 3H-MPP+ uptake was (−)-adrenaline, with an IC50 of 99 (22, 449) μM (n=6). (−)-Adrenaline competitively inhibited 3H-MPP+ uptake, as it significantly increased the Km value of 3H-MPP+ uptake (to 125.4 μM (63.6; 187.1); P〈0.02; n=3) but did not change the Vmax value. The cyanine-derivatives decynium22 and cyanine863 (1-ethyl-2-([1,4-dimethyl-2-phenyl-6-pyrimidinylidene] methyl)quinolinium), which inhibit uptake2 as well as the apical type of the renal transporter for organic cations, potently inhibited 3H-MPP+ uptake with IC50’s of 1.4 (0.4–5.3) (n=6) and 6.5 (2.6–16) (n=4) μM, respectively. Under conditions of monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT) inhibition (with either pargyline (500 μM)+Ro01-2812 (3,5-dinitropyrocatechol; 2 μM) or pargyline (500 μM) +U-0521 (3,4-dihidroxy-2-methyl-propiophenone; 12 μM)), (−)-adrenaline (up to 1 mM) had no inhibitory effect on the uptake of 3H-MPP+. Moreover, the uptake of 3H-MPP+ in the presence of pargyline+Ro 01-2812 was significantly lower (66.9±30.4%; P〈0.05; n=4) than in the absence of these compounds. Therefore, the effect of these MAO and COMT inhibitors on 3H-MPP+ uptake was examined. Interestingly enough, pargyline, Ro 01-2812 and U-0521 were found to inhibit the uptake of 3H-MPP+ (in cells incubated with 200 nM 3H-MPP+): 500 μM pargyline, 2 μM Ro 01-2812 and 100 μM U-0521 decreased the accumulation of 3H-MPP+ to 38.1±6.8 (n=5), 60.5±10.1(n=7) and 71.3±14.5 (n=7) % of control, respectively. It is concluded that 3H-MPP+ is efficiently taken up by rat hepatocytes by a carrier-mediated mechanism sensitive to catecholamines, decynium22 and cyanine863, and to the enzyme inhibitors pargyline, Ro 01-2812 and U-0521.

Notes: Abstract We solve exactly the problem of a one-dimensional repulsive-U Hubbard chain with toroidal boundary conditions (HTB) using the Bethe ansatz approach. We calculate analytically the finite-size corrections to the ground-state energy in the half-filled case and use this expression to derive charge and spin stiffnesses with no assumptions. We then use a “particle-hole” transformation to calculate the finite-size corrections for the half-filledattractive- U case, and again derive the resulting expressions for the charge and spin stiffnesses. Lastly, we discuss how the repulsive-U corrections relate to those of a Heisenberg model with toroidal boundary conditions.