双向发酵——毒性中药炮制减毒的新途径

就现代双向发酵工艺替代传统杂菌发酵工艺,运用于毒性成分分别为生物碱、内酯物质、苷类化合物、毒蛋白、马兜铃酸、蒽醌、鞣质和重金属8类毒性中药炮制减毒的可行性、可靠性进行综合论述。     

Muscle-associated triglyceride measured by computed tomography and magnetic resonance spectroscopy

Objective: Muscle triglyceride can be assessed in vivo using computed tomography (CT) and ¹H magnetic resonance spectroscopy (MRS), two techniques that are based on entirely different biophysical principles. Little is known, however, about the cross‐correlation between these techniques and their test—retest reliability. Research Methods and Procedures: We compared mean muscle attenuation (MA) in soleus and tibialis anterior (TA) muscles measured by CT with intra‐ and extramyocellular lipids (IMCL and EMCL, respectively) measured by MRS in 51 volunteers (26 to 72 years of age, BMI = 25.5 to 39.3 kg/m²). MA of midthighs was also measured in a subset (n = 19). Test—retest measurements were performed by CT (n = 6) and MRS (n = 10) in separate sets of volunteers. Results: MA of soleus was significantly associated with IMCL (r = ?0.64) and EMCL, which by multiple regression analysis was explained mostly by IMCL (p < 0.001) rather than EMCL (β = ?0.010, p = 0.94). Muscle triglyc‐eride was lower in TA than in soleus, and MA of TA was significantly correlated with EMCL (r = ?0.40) but not IMCL (r = ?0.16). By CT, MA of midthighs was correlated with MA in soleus (r = 0.40, p = 0.07) and whole calf (r = 0.62, p < 0.05). Finally, both MA and IMCL were highly reliable in soleus (coefficient of variation = <2% and 6.7%, respectively) and less reliable in TA (4% and 10%, respectively). Discussion: These results support the use of both CT and MRS as reliable methods for assessing skeletal muscle lipid.     

Formulation of the CBC-Model for Modelling the Contaminants and Footprints in Natural Attenuation of BTEX

This paper provides the details of the Coupled Biological and Chemical (CBC) model for representing in situ bioremediation of BTEX. The CBC model contains novel features that allow it to comprehensively track the footprints of BTEX bioremediation, even when the fate of those footprints is confounded by abiotic reactions and complex interactions among different kinds of microorganisms. To achieve this comprehensive tracking of all the footprints, the CBC model contains important new biological features and key abiotic reactions. The biological module of the CBC-model includes these important new aspects: (1) it separates BTEX fermentation from methanogenesis, (2) it explicitly includes biomass as a sink for electrons and carbon, (3) it has different growth rates for each biomass type, and (4) it includes inhibition of the different reactions by other electron acceptors and by sulfide toxicants. The chemical module of the CBC-model includes abiotic reactions that affect the footprints of the biological reactions. In particular, the chemical module describes the precipitation/dissolution of CaCO3, Fe2O3, FeS, FeS2, and S degrees. The kinetics for the precipitation/dissolution reactions follow the critical review in Maurer & Rittmann (2004).     

Challenges in Monitoring the Natural Attenuation of Spatially Variable Plumes

Monitored natural attenuation may be applied as a risk-based remediation strategy if it can be established that contaminants are or will be reduced to some acceptable level at or before a compliance point. Contaminant attenuation is often attributed to intrinsic biodegradation, which in some circumstances may occur only at the plume fringes where electron acceptors from the surrounding uncontaminated zones mix by dispersion and diffusion with the plume. However, due to the common spatial and temporal variability exhibited by many plumes, the centreline monitoring approaches advocated in many natural attenuation protocols may be unable to detect natural attenuation occurring primarily by fringe processes. Snapshot data from a multilevel sampling well transect across an MTBE plume at Vandenberg Air Force Base, CA, USA, illustrate the difficulty of centreline monitoring and the challenge of providing sufficient detail to detect attenuation processes that may be occurring primarily at plume fringes. In a study of a phenols plume in Wolverhampton, UK, high-resolution multilevel wells demonstrated that the key biodegradation processes were restricted spatially to the upper fringe of the plume and were rate-limited by transverse dispersion and diffusion of electron acceptors into the plume. Thus the overall extent of biodegradation was considerably less than suggested by a plume-scale analysis of total electron acceptor and contaminant budgets. These examples indicate that more robust and cost-effective MNA assessments can be obtained using monitoring strategies that focus on the location of key biodegradation processes.     

Listeria monocytogenes mediated CFTR transgene transfer to mammalian cells

Background

Several approaches for gene therapy of cystic fibrosis using viral and non‐viral vectors are currently being undertaken. Nevertheless, the present data suggest that vectors currently being used will either have to be further modified or, alternatively, novel vector systems need to be developed. Recently, bacteria have been proven as suitable vehicles for DNA transfer to a wide variety of eukaryotic cells. In this study, we assessed the ability of the facultative intracellular pathogen Listeria monocytogenes to deliver a cDNA encoding the human cystic fibrosis transmembrane conductance regulator (CFTR) to CHO‐K1 cells, since these cells have been extensively used for heterologous CFTR expression.

Methods

An established in vitro gene transfer system based on antibiotic‐mediated lysis of intracellular L. monocytogenes was exploited to transfer eukaryotic expression plasmids. Transient as well as stable CFTR transgene expression was analyzed by microscopical and biochemical methods; functionality was tested by whole‐cell patch‐clamp recordings.

Results

L. monocytogenes mediated gene transfer to CHO‐K1 cells was facilitated by an improved transfection protocol. In addition, the use of the isogenic mutant L. monocytogenes hlyW491A, engineered to produce a hemolysin variant with low toxigenic activity, greatly enhanced the efficiency of gene transfer. This strain allowed the transfer of functional CFTR to CHO‐K1 cells.

Conclusions

This is the first demonstration of L. monoyctogenes mediated CFTR transgene transfer. The successful in vitro transfer suggests that L. monocytogenes might be a potential vector for cystic fibrosis gene therapy or alternative applications and deserves further investigation in vitro as well as in vivo. Copyright © 2002 John Wiley & Sons, Ltd.

     

Evaluation of Natural Attenuation of Benzene and Dichloroethanes at the KL Landfill

Natural attenuation of benzene and dichloroethanes in groundwater contaminated by leachate from the West KL Avenue landfill in Kalamazoo, Michigan, was evaluated in three phases. Existing data from the previous site investigations were used to locate a series of high-resolution vertical profile samples. By analyzing data from the discrete vertical profile samples, the rates of attenuation of benzene and dichloroethanes in the plume were forecasted. Permanent monitoring wells were installed over the depth intervals associated with high concentrations in the vertical profile sampling. These wells were monitored over time to extract independent estimates of the rates of degradation of benzene and dichloroethanes. Estimates of first-order attenuation rate constants were obtained using two methods: a method due to Buscheck and Alcantar (1995), which is based on a one-dimensional steady-state analytical solution, and the tracer correction method of Wiedemeier et al. (1996). The rates of attenuation predicted from the vertical profile sampling were found to be in good agreement with the rates obtained from the permanent monitoring well data, indicating that the long-term behavior of the contaminant plumes is consistent with the initial forecast. The results also indicated that the natural attenuation of benzene, 1,1-dichloroethane (DCA), and 1,2-DCA was statistically significant (at the 0.05 level).     

Behavioural evidence that magnetic field effects in the land snail,Cepaea nemoralis,might not depend on magnetite or induced electric currents

Although extremely low frequency (ELF) magnetic fields (<300 Hz) appear to exert a variety of biological effects, the magnetic field sensing/transduction mechanism(s) remains to be established. Here, using the inhibitory effects of magnetic fields on endogenous opioid peptide-mediated “analgaesic” response of the land snail. Cepaea nemoralis, we addressed the mechanism(s) of action of ELF magnetic fields. Indirect mechanisms involving both induced electric fields and direct magnetic field detection mechanisms (e.g., magnetite, parametric resonance) were evaluated. Snails were exposed to a static magnetic field (B_DC=78±1 μT) and to a 60 Hz magnetic field (B_AC=299±1 μT peak) with the angle between the static and 60 Hz magnetic fields varied in eight steps between 0° and 90°. At 0° and 90°, the magnetic field reduced opioid-induced analgaesia by approximately 20%, and this inhibition was increased to a maximum of 50% when the angle was between 50° and 70°. Because B_AC was fixed in amplitude, direction, and frequency, any induced electric currents would be constant independent of the B_AC/B_DC angle. Also, an energy transduction mechanism involving magnetite should show greatest sensitivity at 90°. Therefore, the energy transduction mechanism probably does not involve induced electric currents or magnetite. Rather, our results suggest a direct magnetic field detection mechanism consistent with the parametric resonance model proposed by Lednev. © 1996 Wiley-Liss, Inc.     

Limnology of two lake systems of Katmai National Park and Preserve, Alaska: Part II. Light penetration and Secchi depth

Seven large lakes in the Naknek River drainage and four in the Alagnak River drainage within the Katmai National Park and Preserve, Alaska, were surveyed once a summer during the period 1990–92 to determine baseline limnological conditions. All of the lakes are oligotrophic based on Secchi depth (SD) transparency and light penetration. Overall, SD transparency varied from 4.4 m to 17 m, the vertical light extinction coefficient (K _d) ranged from 0.411 m^-1 to 0.070 m^-1 and the depth of 1% light penetration (I_1%) varied from 11 m to 67 m. However, because of greater light scattering, the percent of photosynthetic radiation (PAR) at SD was nearly twice as much in Battle Lake (30.4%) and Naknek Lake (32.8%), compared with the other nine lakes (mean 16%). Consequently, the ratio of I_1% to SD was about 4 in these two lakes compared to a mean value of 2.6 for the other lakes. However, Battle Lake is a deep blue calcium sulfate lake with little phytoplankton, whereas Naknek Lake contains some inorganic glacial flour and volcanic ash, as well as planktonic algae, but where sampled exhibits minimal turbidity. Biomass of planktonic algae (indexed by total chlorophyll concentration) explained most of the variation in SD (r ²=0.66), K _d (r ²=0.75), and I _1% (r ²=0.85). In contrast, neither color nor turbidity were significant predictors of any optical variable. Considering all 11 lakes, there was a significant linear relationship between SD and both K _d (r ²=0.80) and I _1% (r ²=0.72); however, most of the unaccounted for variation was attributed to Battle Lake and Naknek Lake. Although changes in water transparency are often linked to changes in algal biomass (chlorophyll), simple measures of SD transparency alone may not be appropriate for assessing whole-scale watershed or regional changes toward oligotrophication or eutrophication in lakes of the remote and pristine Katmai National Park and Preserve.     

Xanthophyll-cycle dynamics and rapid induction of anthocyanin synthesis in Eucalyptus nitens seedlings transferred to photoinhibitory conditions

The effects of rapid induction and subsequent relaxation of cold-induced photo-inhibition on pigment chemistry of Eucalyptus nitens (Deane and Maiden) Maiden seedling leaves was assessed. The seedlings were subjected to four treatments in a nursery, fertilised or non-fertilised and shaded or non-shaded, before induction of photoinhibition in a growth chamber. Within 2 days, growth chamber conditions decreased photochemical efficiency (Fv/Fm) and increased xanthophyll-cycle conversion ratio. This was associated with decreased levels of total chlorophyll and increased levels of xanthophyll-cycle pigments. After 8 days, Fv/Fm of all treatments rose. Anthocyanin Levels gradually increased until day eight, except in non-shaded, non-fertilised seedlings, which had high levels before the induction of photoinhibition. Visible spectroscopy indicated increased absorption between 500 and 590nm, indicative of anthocyanin absorption. Electron transport rate after xanthophyll-cycle relaxation was half that measured before induction of photoinhibition. The findings indicate that anthocyanins may provide a photoprotective role in E. nitens seedlings under conditions of photoinhibition.     

Development of a PCR method for the detection and quantification of benzoyl-CoA reductase genes and its application to monitored natural attenuation

Benzoyl coenzyme A reductase (BCR) catalyzes dearomatization of benzoyl coenzyme A (benzoyl-CoA), which is the central step in the anaerobic degradative pathways for a variety of aromatic compounds. This study developed a PCR method for the detection and quantification of BCR genes in bacterial strains and environmental samples. PCR primers were designed by aligning known BCR genes in Thauera, Azoarcus and Rhodopseudomonas species, and their utility was assessed by amplifying BCR fragments from aromatic-hydrocarbon degrading anaerobes and other bacteria. BCR fragments with the expected sizes were obtained from denitrifying and phototrophic aromatics degraders. The positive signals were also obtained from Geobacter metallireducens and xylene-degrading sulfate-reducing bacterium (strain mXyS1) but not from other aromatics-degrading sulfate-reducing bacteria and aerobic bacteria. When the PCR was used for analyzing a natural attenuation (NA) site, the positive signal was obtained only from gasoline-contaminated groundwater; sequence analysis of these amplicons revealed that most of them exhibited substantial similarities to the known BCRs. Quantitative competitive PCR analysis estimated BCR-gene copies to account for 10–40% of bacterial 16S rRNA gene copies in the contaminated groundwater, indicating that bacteria possessing BCR genes were highly enriched in the contaminated groundwater. In microcosm bioremediation tests using the contaminated groundwater, the copy number of BCR gene was approximately 10-fold increased in the course of aromatics degradation under denitrifying conditions but not under sulfidogenic conditions. These results suggest the utility of the PCR method for assessing the potential of denitrifying bacteria for aromatic-compound degradation in groundwater.