Residual effects of 3,4-dichloroaniline on offspring born to Ceriodaphnia cf. dubia exposed for multiple generations

One of the acknowledged limitations ofconventional toxicity tests is their inabilityto evaluate the impact of toxicants onsubsequent generations. Given their relativelyshort lifespan, cladocerans in the field may beexposed to toxicants for several generations.However, it is unclear what effect such anexposure regime could have on the cladoceranfitness after removal of the toxicant. Thispaper aimed to determine the offspring fitnessof juveniles produced by adult Ceriodaphnia cf. dubia exposed toresidual levels of 3,4-dichloroaniline overfour generations. Mass cultures of Ceriodaphnia cf. dubia were maintainedfor several generations in variousconcentrations of 3,4-dichoroaniline (0, 2.5,5, 10, 15 and 20 µg/L). The mass cultureswere re-established every generation using4th brood neonates <24 h old. Eachgeneration, 4th brood neonates <24 h oldwere also transferred individually intotoxicant-free water and examined until theproduction of their 3rd brood. F1offspring of mothers exposed to 15 and20 µg/L 3,4-dichloroaniline showedsignificantly (p < 0.05) reducedreproduction compared to the controls. Nosignificant (p > 0.05) changes inreproduction due to 3,4-dichloroaniline wereobserved for the F2 and F3 offspring. However,F4 offspring of mothers exposed to all3,4-dichloroaniline concentrations showedsignificantly (p < 0.05) increasedreproduction compared to the controls. Possibleexplanations for the varying influence ofmaternal 3,4-dichloroaniline exposure on thereproductive output of the offspring arediscussed.     

Changes in the Glutamate Release and Uptake of Cerebellar Cells in Perinatally Nicotine-Exposed Rat Pups

Cerebellar granule and glial cells were cultured from 7 day-old rat pups after pre- and post-natal nicotine treatment. Ten days later, the basal release of glutamate in the granule cells prepared from the pre- and post-natally nicotine-exposed pups was higher and lower than the controls, respectively. The N-methyl-D-aspartate-induced release of glutamate was higher in the granule cells of post-natal nicotine exposed rats. However, the nicotine-induced glutamate release was either unchanged or was lower in the granule cells of all nicotine-treated pups. The basal glutamate uptake was higher in the glial cells from those exposed pre-natally and lower in the continuously nicotine-exposed pups. The sensitivities of L-trans-pyrrolidine-2,4-dicarboxylic acid on glutamate uptake were higher in all nicotine treated groups. There was a higher number of specific [³H]dizocilpine binding sites in the pre- or continuously nicotine-exposed group. These results suggest that the cerebellar cell properties are altered after perinatal nicotine exposure and that the development of an excitatory amino acid system might be affected differently depending on the nicotine exposure time.     

Treatment with a copper-zinc chelator markedly and rapidly inhibits beta-amyloid accumulation in Alzheimer's disease transgenic mice.

Inhibition of neocortical beta-amyloid (Abeta) accumulation may be essential in an effective therapeutic intervention for Alzheimer's disease (AD). Cu and Zn are enriched in Abeta deposits in AD, which are solubilized by Cu/Zn-selective chelators in vitro. Here we report a 49% decrease in brain Abeta deposition (-375 microg/g wet weight, p = 0.0001) in a blinded study of APP2576 transgenic mice treated orally for 9 weeks with clioquinol, an antibiotic and bioavailable Cu/Zn chelator. This was accompanied by a modest increase in soluble Abeta (1.45% of total cerebral Abeta); APP, synaptophysin, and GFAP levels were unaffected. General health and body weight parameters were significantly more stable in the treated animals. These results support targeting the interactions of Cu and Zn with Abeta as a novel therapy for the prevention and treatment of AD.     

Degradation of 1,3-dichloropropene by a soil bacterial consortium and Rhodococcus sp. AS2C isolated from the consortium

A bacterial consortium capable of degrading the fumigant 1,3-D ((Z)- and (E)-1,3-dichloropropene) was enriched from an enhanced soil. This mixedculture degraded (Z)- and (E)-1,3-D only in the presence of a suitable biodegradable organic substrate, such as tryptone, tryptophan, or alanine. After 8 months of subculturing at 2- to 3-week intervals, a strain of Rhodococcus sp. (AS2C) that was capable of degrading 1,3-D cometabolically in the presenceof a suitable second substrate was isolated. (Z)-3-chloroallyl alcohol (3-CAA) and (Z)-3-chloroacrylic acid (3-CAAC), and (E)-3-CAA and (E)-3-CAAC were the metabolites of (Z)- and (E)-1,3-D, respectively. (E)-1,3-D was degraded faster than (Z)-1,3-D by the strain AS2C and the consortium. AS2C also degraded (E)-3-CAA faster than (Z)-3-CAA. Isomerization of (E)-1,3-D to (Z)-1,3-D orthe (Z) form to the (E) form did not occur.     

A nonsingular optimization approach to the feed rate profile optimization of fedbatch cultures

A new method to calculate the optimal feed rate profile for fedbatch culture is proposed. Instead of the usual singular control approach of taking the feed rate as the control variable, the substrate concentration profile is used as the transformed control variable to avoid the computational difficulty associated with the singular control. Thus, the problem is converted into a nonsingular optimization problem of determining the optimal substrate concentration profile subject to a constraint. The equivalent feed rate profile to match the optimal substrate concentration profile is then generated. With this method the computational difficulty associated with singular controls for high-order systems is circumvented. The proposed method is illustrated by a number of examples.     

多因素影响白花前胡甲素和乙素含量分析

目的:研究在不同采收期、栽培环境、抽薹前后和组织部位的白花前胡甲素和乙素含量的变化规律.方法:采用高效液相色谱法测定不同采收时期栽培白花前胡甲素及乙素含量.结果:前胡甲素及乙素含量累积规律是根>茎>叶;二年生前胡甲素含量显著高于一年生,南坡前胡甲素显著高于其他坡向;抽薹前后的前胡甲素和乙素含量无显著差异.结论:高效液相...     

Standing-gradient osmotic flow Examination of its validity using an analytical method

The solutions to the non-linear differential equations governing solute-solvent coupling in the intercellular spaces of epithelial layers have been obtained by using an analytical method, rather than the usual numerical ones. When the present series solution includes second-order correction terms, the concentration and velocity profiles obtained by the analytical method agree very well with those coming from numerical solutions. This method has further allowed us to examine the standing-gradient hypothesis when applied to the backwards fluid transport system of the corneal endothelium. With the information presently available for the relevant parameters (osmotic permeability, rate of transport, radius and length of the spaces, and location of the pumping sites), near-isotonicity of the transported fluid would not be explained by the standing-gradient model.