Molecular phylogeny of wood mice (Apodemus, Muridae) in East Asia

Sequences of the mitochondrial cytochrome b (1140 bp) and nuclear IRBP (1152 bp) genes were used to assess the evolutionary history of Apodemus, using the complete set of Asian species. Our results indicate that speciation in Asia involved three radiations, which supports an earlier study. The initial radiation yielded A. argenteus (Japanese endemic), A. gurkha (Nepalese endemic), and the ancestral lineage of the remaining Asian species. This lineage subsequently diverged into four groups: agrarius-chevrieri (agrarius group), draco-latronum-semotus (draco group), A. peninsulae, and A. speciosus (Japanese endemic). The final step consisted of divergence within two species groups as a consequence of the geography of the Yunnan-Guizhou plateau and Taiwan. The ecological ability of two Apodemus-species to inhabit one locality via niche partitioning likely drove the second radiation and shaped the basic geographical pattern seen today: A. argenteus and A. speciosus in Japan, A. agrarius and A. peninsulae in northern China, and the A. agrarius and A. draco groups in southern China. The three radiations are estimated to have occurred 7.5, 6.6, and 1.8-0.8 Mya respectively, using the IRBP clock, based on rat-mouse divergence 12 Mya. (C) 2003 The Linnean Society of London.

Molecular phylogeny and taxonomy of wood mice (genus Apodemus Kaup, 1829) based on complete mtDNA cytochrome b sequences, with emphasis on Chinese species

Phylogenetic relationships among 15 species of wood mice (genus Apodemus) were reconstructed to explore some long-standing taxonomic problems. The results provided support for the monophyly of the genus Apodemus, but could not reject the hypothesis of paraphyly for this genus. Our data divided the 15 species into four major groups: (1) the Sylvaemus group (A. sylvaticus, A. flavicollis, A. alpicola, and A. uralensis), (2) the Apodemus group (A. peninsulae, A. chevreri, A. agrarius, A. speciosus, A. draco, A. ilex, A. semotus, A. latronum, and A. mystacinus), (3) A. argenteus, and (4) A. gurkha. Our results also suggested that orestes should be a valid subspecies of A. draco rather than an independent species; in contrast, A. ilex from Yunnan may be regarded as a separate species rather than a synonym of orestes or draco. The species level status of A. latronum, tscherga as synonyms of A. uralensis, and A. chevrieri as a valid species and the closest sibling species of A. agrarius were further corroborated by our data. Applying a molecular clock with the divergences of Mus and Rattus set at 12 million years ago (Mya) as a calibration point, it was estimated that five old lineages (A. mystacinus and four major groups above) diverged in the late Miocene (7.82-12.74 Mya). Then the Apodemus group (excluding A. mystacinus) split into two subgroups: agrarius and draco, at about 7.17-9.95 Mya. Four species of the Sylvaemus group were estimated to diverge at about 2.92-5.21 Mya. The Hengduan Mountains Region was hypothesized to have played important roles in Apodemus evolutionary histories since the Pleistocene. (C) 2004 Elsevier Inc. All rights reserved.

Aerobic biodegradation of hexachlorobenzene by an acclimated microbial community

The aerobic degradation of hexachlorobenzene (HCB) by an acclimated microbial community which isolated from a contaminated site and acclimated in our laboratory was investigated. The enriched microbial community was capable of biodegrading HCB when cultivated in minimal salts medium and supplied HCB as the sole carbon source. The efficiencies of microbial community in the degradation of HCB under different pH and temperatures were examined. The phylogenetic analysis for the nearly complete sequences of 16S rDNA demonstrated that the bacteria assemblage in the microbial community was dominated by Azospirillum and Alcaligenes groups.

Biodegradation of dibenzofuran by Janibacter terrae strain XJ-1

The dibenzofuran (DF)-degrading bacterium, Janibacter terrae strain XJ-1, was isolated from sediment from East Lake in Wuhan, China. This strain grows aerobically on DF as the sole source of carbon and energy; it has a doubling time of 12 hours at 30 degrees C; and it almost completely degraded 100 mg/L-1 DF in 5 days, producing 2,2',3-trihydroxybiphenyl, salicylic acid, gentisic acid, and other metabolites. The dbdA (DF dioxygenase) gene cluster in the strain is almost identical to that on a large plasmid in Terrabacter sp. YK3. Unlike Janibacter sp. strain YY-1, XJ-1 accumulates gentisic acid rather than catechol as a final product of DF degradation.

Enzymatic activities in constructed wetlands and di-n-butyl phthalate (DBP) biodegradation

The bioaccumulation of phthalate acid esters (PAEs) from industrial products and their mutagenic action has been suggested to be a potential threat to human health. The effects of the most frequently identified PAE, Di-n-butyl phthalate (DBP), and its biodegradation, were examined by comparison of two small scale plots (SSP) of integrated vertical-flow constructed wetlands. The influent DBP concentration was 9.84 mg l(-1) in the treatment plot and the control plot received no DBP. Soil enzymatic activities of dehydrogenase, catalase, protease, phosphatase, urease, cellulase, beta-glucosidase, were measured in the two SSP after DBP application for 1 month and 2 months, and 1 month after the final application. Both treatment and control had significantly higher enzyme activity in the surface soil than in the subsurface soil (P < 0.001) and greater enzyme activity in the down-flow chamber than in the up-flow chamber (P < 0.05). In the constructed wetlands, DBP enhanced the activities of dehydrogenase, catalase, protease, phosphatase and inhibited the activities of urease, cellulase and beta-glucosidase. However, urease, cellulase, beta-glucosidase activities were restored 1 month following the final DBP addition. Degradation of DBP was greater in the surface soil and was reduced in sterile soil, indicating that this process may be mediated by aerobic microorgansims. DBP degradation fitted a first-order model, and the kinetic equation showed that the rate constant was 0.50 and 0.17 d(-1), the half-life was 1.39 and 4.02 d, and the r(2) was 0.99 and 0.98, in surface and subsurface soil, respectively. These results indicate that constructed wetlands are able to biodegrade organic PA-Es such as DBP. (c) 2005 Elsevier Ltd. All rights reserved.

Study of sorption, biodegradation and isomerization of HCH in stimulated sediment/water system

This paper reported the sorption, biodegradation and isomerization of hexachlorocyclohexane (HCH) in laboratory sediment/water system under aerobic and anaerobic conditions, respectively. The effect of organic nutrient addition to the sorption of HCH was also investigated. It indicates that HCH is highly adsorbed on sediments under both conditions. During the tests, the biodegradation and isomerization of HCH were dramatically speeded up after organic nutrient additions, especially in the case of the observation under aerobic condition. It was found, beta-HCH was the most persistent in the environment, that is due to the isomerization of alpha-HCH in a big amount to beta-HCH, besides its chemical stability. (C) 1997 Elsevier Science Ltd.

The Deposition and Burning Characteristics During Slagging Co-Firing Coal and Wood: Modeling and Numerical Simulation

Numerical analysis was used to study the deposition and burning characteristics of combining co-combustion with slagging combustion technologies in this paper. The pyrolysis and burning kinetic models of different fuels were implanted into the WBSF-PCC2 (wall burning and slag flow in pulverized co-combustion) computation code, and then the slagging and co-combustion characteristicsespecially the wall burning mechanism of different solid fuels and their effects on the whole burning behavior in the cylindrical combustor at different mixing ratios under the condition of keeping the heat input samewere simulated numerically. The results showed that adding wood powder at 25% mass fraction can increase the temperature at the initial stage of combustion, which is helpful to utilize the front space of the combustor. Adding wood powder at a 25% mass fraction can increase the reaction rate at the initial combustion stage; also, the coal ignitability is improved, and the burnout efficiency is enhanced by about 5% of suspension and deposition particles, which is helpful for coal particles to burn entirely and for combustion devices to minimize their dimensions or sizes. The results also showed that adding wood powder at a proper ratio is helpful to keep the combustion stability, not only because of the enhancement for the burning characteristics, but also because the running slag layer structure can be changed more continuously, which is very important for avoiding the abnormal slag accumulation in the slagging combustor. The theoretic analysis in this paper proves that unification of co-combustion and slagging combustion technologies is feasible, though more comprehensive and rigorous research is needed.

Kinetic modeling of growth and biodegradation of phenol and m-cresol using Alcaligenes faecalis

A phenol-degrading. microorganism, Alcaligenes faecalis, was used to study the substrate interactions during cell growth on phenol and m-cresol dual substrates. Both phenol and m-cresol could be utilized by the bacteria as,the sole carbon and energy sources. When cells grew on the mixture of phenol and m-cresol, strong substrate interactions were observed. m-Cresol inhibited the degradation of phenol, on the other hand, phenol also inhibited the utilization of m-cresol, the overall cell growth rate was the co-action of phenol and m-cresol. In addition, the cell growth and substrate degradation kinetics of phenol, m-cresol as single and mixed substrates for A. faecalis in batch cultures were also investigated over a wide range of initial phenol concentrations (10-1400 mg L-1) and initial m-cresol concentrations (5-200 mg L-1). The single-substrate kinetics was described well using the Haldane-type kinetic models, with model constants of it mu(m1) = 0.15 h(-1), K-S1 = 2.22 mg L-1 and K-i1 = 245.37 mg L-1 for cell growth on phenol and mu(m2) = 0.0782 h(-1), K-S2 = 1.30 mg L-1 and K-i2 = 71.77 mgL(-1), K-i2' = 5480 (mg L-1)(2) for cell growth on m-cresol. Proposed cell growth kinetic model was used to characterize the substrates interactions in the dual substrates system, the obtained parameters representing interactions between phenol and m-cresol were, K = 1.8 x 10(-6), M = 5.5 x 10(-5), Q = 6.7 x 10(-4). The results received in the experiments demonstrated that these models adequately described the dynamic behaviors of phenol and m-cresol as single and mixed substrates by the strain of A. faecalis.

Biodegradation of poly(L-lactide-co-glycolide) tube stents in bile

The objective of this study was to evaluate degradation behavior and the feasibility of biodegradable polymeric stents in common bile duct (CBD) repair and reconstruction. Various molar ratios of lactide (LA) and glycolide (GA) in poly(L-lactide-co-glycolide) (PLGA) were synthesized and processed into a circular tubing of similar to 10.0 mm outer diameter and a wall thickness of about 2.0 mm.