Differentiation of subspecies of asiatic striped squirrels (Tamiops swinhoei) (Milne-Edwards) (Rodentia : Sciuridae) in China with description of a new subspecies

Based on the pelage characteristics and results of multivariate and univariate analyses, a new subspecies is described in this study, and a taxonomic revision of Tamiops swinhoei from China is presented. In total, 123 specimens of Tamiops swinhoei were in

THE ORIGIN AND GENETIC DIFFERENTIATION OF NATIVE BREEDS OF PIGS IN SOUTHWEST CHINA - AN APPROACH FROM MITOCHONDRIAL-DNA POLYMORPHISM

Mitochondrial DNA (mtDNA) of six breeds of native domestic pigs from Yunnan province, southwest China, and two wild boars obtained from Sichuan, China, and Vietnam was analyzed using 20 restriction endonucleases that recognize six nucleotides. Restriction maps were made by double-digestion methods and polymorphic sites were located on the map. According to their mtDNA restriction types, all the breeds were classified into six groups. Genetic distances among groups were calculated to define their phylogenetic relationships. The relationship between the Sichuan wild boar and domestic pigs is close, while the Vietnamese wild boar is relatively far from them, so the domestic pigs in southwest China are likely to have originated from a wild pig which distributed in west China. We compare our results with previous reports in literature and discuss the relationship among Chinese pigs, Japanese pigs, and European pigs. The mtDNA cleavage pattern of the Mingguang pig digested by EcoRV was identical to that of Duroc; mutations at the EcoRI site, detected in the mtDNA of two Dahe pigs, are the same as in the Vietnamese wild boar, suggesting that mutational hot spots exist in the mtDNA of pigs.

Characteristics of the microbial communities in the integrated vertical-flow constructed wetlands

Microorganisms play an important role in removing pollutants from constructed wetlands. We investigated the microbial characteristics in a novel integrated vertical-flow constructed wetland (IVCW), which has been in operation in Wuhan, China since 1998. We used phospholipid fatty acid (PLFA) and amoA gene to analyze the structure and diversity of the microbial community within the IVCW. PLFA results suggested that the amount of bacterial PLFA was significantly higher than that of fungal PLFA, but the total microbial biomass represented by PLFA index was low in the system. Microbial spatial distribution showed significantly higher bacterial (both G(+) and G(-)) and fungal biomass in the surface than in the subsurface layers. The ratios of monounsaturated to branched PLFA demonstrated that an anaerobic layer sandwiched by two aerobic layers existed in the IVCW, consistent with the redox potential results. Analysis of the amoA revealed the presence of Nitrosomonas-like sequences in the surface substrate of the downflow chamber and apparent diversities of ammonia-oxidizing bacteria in the system. These results suggest that microorganisms, despite their relatively low biomass, have inhabited the IVCW, and the results will offer some valuable information on microbe to system designers and managers.

VERTICAL DISTRIBUTIONS OF SIZE-FRACTIONATED IRON IN THREE TYPICAL BAYS OF LAKE DIANCHI (CHINA)

In order to elucidate the vertical distributions of iron in three typical bays (Haigeng bay, Macun bay and Haidong bay) of Lake Dianchi (China), the investigation was conducted on March, 2003. Results showed that the vertical distributions were influenced by monsoon, cyanobacterial bloom and water depth as well as sediment resuspension, which indicated that their translocations and transformations were decided by geographical and physical as well as chemical and biological characteristics.

Population genetic structure and geographical differentiation of the Chinese catfish Hemibagrus macropterus (Siluriformes, Bagridae): Evidence for altered drainage patterns

National Natural Science Foundation of China (NSFC) [2007CB411600, 30530120]

Effects of Cd2+ and Pb2+ on the substrate biofilms in the integrated vertical-flow constructed wetland

The effects of single Cd2+ and Pb2+, and combined Cd2+ and Pb2+ on dehydrogenase activity and polysaccharide content of the substrate biofilms in the integrated vertical-flow constructed wetland (IVCW) were studied. Dehydrogenase activities decreased linearly with the increasing concentrations of Cd2+ and Pb2+ at different times (6, 24, 72, and 120 h). The activities at both 6 and 24 h were significantly higher than that at 72 and 120 h in the case of single and combined treatments. The single Cd2+ and Pb2+ treatments significantly inhibited dehydrogenase activities at concentrations in excess of 20 mu mol/L Cd2+ and 80 mu mol/L Pb2+, respectively. The inhibitory effect of Cd2+ was much greater than that of Pb2+. At the same time, the combined treatment of Cd2+ and Pb2+ Significantly inhibited dehydrogenase activities at all five concentrations studied and the lowest combined concentration was 1.25 mu mol/L Cd2+ and 5 mu mol/L Pb2+. A synergistic effect of Cd2+ and Pb2+ was observed. On the other hand, polysaccharide contents varied unpredictably with the increasing concentrations of Cd2+ and Pb2+ and extended experimental time. There were no significant statistical differences within the range of concentration and time studied, whether singly or in combination. These results implied that the effects of heavy metals on biofilms should be a concern for the operation and maintenance of constructed wetlands.

Population differentiation of Procypris rabaudi (Tchang) in the upper reaches of the Yangtze River revealed by mitochondrial DNA and RAPD markers

Procypris rabaudi (Tchang) is a cyprinid fish endermic to middle and upper reaches of the Yangtze River. Besides in main stream and large tributaries, there exists an early matured, small-sized ecological type in a small tributary, Tang River. In this study, mitochondrial DNA cytochrome h (cyt b) gene sequence analysis and randomly amplified polymorphic DNA (RAPD) analysis were performed to investigate the differentiation of the Tang River population from the Mudong reach population of the Yangtze River, with the purpose of conservation and exploitation of this fish. In the 1140 bps of cyt b gene sequence surveyed, 20 sites were found polymorphic, which defined 23 haplotypes. Among them, four haplotypes accounted for 54.4% of all individuals, while population-specific haplotypes occurred in low frequencies. Analysis of molecular variation on cyt b data revealed no significant partition existing between Tang River population and Mudong reach population. Analyses of 132 RAPD loci suggested that genetic variation between populations was significant, though values of different F-ST were not very high. The results revealed low genetic diversity and the beginning of population differentiation, suggesting that Tang River population should be designated as a separate Management Unit.

Effects of nutrients on the substrate biofilms in the integrated vertical-flow constructed wetland

A L9 orthogonal array design involving 3 factors (C6H12O6, KNO3 and NaH2PO4) and 3 levels for each (C6H12O6: 0.2, 0.4 or 0.8 g/L; KNO3: 0.4, 0.8 or 1.6 g/L, NaH2PO4: 0.05, 0.1 or 0.2 g/L), was used to study the effects of nutrients on dehydrogenase activity and polysaccharide content of substrate biofilms in the integrated vertical-flow constructed wetland (IVCW). Results showed that C6H12O6 and KNO3 were the main factors for dehydrogenase activity and polysaccharide content of biofilms, respectively. The combinations of three nutrients at different concentrations had different effects on dehydrogenase activity and polysaccharide content of biofilms. The optimal combination for dehydrogenase activity was obtained by locating the concentrations Of C6H12O6, KNO3 and NaH2PO4 at 0.2, 0.8 and 0.05 g, and the optimal combination for polysaccharide content was obtained by locating the concentrations Of C6H12O6, KNO3 and NaH2PO4 at 0.2, 0.4 and 0.2 g/L, respectively. The corresponding maximum activity and polysaccharide content were 5.40 mu g TF/g substrate/12 h and 3454.6 mu g/g substrate, respectively. These results would provide the laboratory foundation for optimizing the purification function of the wetland systems.

Differentiate performance of eight filter media in vertical flow constructed wetland: Removal of organic matter, nitrogen and phosphorus

A comparative study was conducted to reveal the differentiate effects of eight different filter media including gravel, zeolites, anthracite, shale, vermiculite, ceramic filter media, blast furnace steel slag and round ceramsite. The study mainly related to the eight different filter media's removal performances of organic matter, nitrogen and phosphorus in the vertical flow constructed wetland simulated system, which treating wastewater at hydraulic loading rate of 1000-2500 mm/d. The results indicated that the removal effects were closely related to the physical and chemical properties of medium materials. Anthracite-filled system had the highest removal rate for the total organic carbon (TOC), up to 70%, and the removal rates of other systems ranged from 20% to 30%. As for the five-day biochemical oxygen demand (BOD5), anthracite-filled and steel slag-filled systems had the highest removal rates, also up to 70%, as well as other systems all exceeded 50%. At the same time, for the total nitrogen (TN) and NH4(+)-N, the zeolites-filled and ceramic-filled systems had the best performances with the removal rates of more than 70%, the other way round, the removal rates of other systems were only about 20%. The distinguishable effects were also observed in removal performances of total phosphorus (TP) and total dissoluble phosphorus (TDP). The removal rates of TP and TDP in steel slag-filled systems were more than 90%, a much higher value, followed by that of the anthracite-filled system, more than 60%, but those of other systems being the less. Our study provided a potential mechanism to optimize the filter media design for the vertical flow constructed wetlands.

A gene cluster that regulates both heterocyst differentiation and pattern formation in Anabaena sp strain PCC 7120

Wild-type Anabaena sp. strain PCC 7120, a filamentous nitrogen-fixing cyanobacterium, produces single heterocysts at semi-regular intervals. asr0100 (patU5) and alr0101 (patU3) are homologous to the 5' and 3' portions of patU of Nostoc punctiforme. alr0099 (hetZ) overlaps the 5' end of patU5. hetZ, patU5 and patU3 were all upregulated, or expressed specifically, in proheterocysts and heterocysts. Mutants of hetZ showed delayed or no heterocyst differentiation. In contrast, a patU3 mutation produced a multiple contiguous heterocyst (Mch) phenotype and restored the formation of otherwise lost intercalary heterocysts in a patA background. Decreasing the expression of patU3 greatly increased the frequency of heterocysts in a mini-patS strain. Two promoter regions and two principal, corresponding transcripts were detected in the hetZ-patU5-patU3 region. Transcription of hetZ was upregulated in a hetZ mutant and downregulated in a patU3 mutant. When mutants hetZ::C.K2 and hetZ::Tn5-1087b were nitrogen-deprived, P-hetC-gfp was very weakly expressed, and in hetZ::Tn5-1087b, P-hetR-gfp was relatively strongly expressed in cells that had neither a regular pattern nor altered morphology. We conclude that the hetZ-patU5-patU3 cluster plays an important role in co-ordination of heterocyst differentiation and pattern formation. The presence of homologous clusters in filamentous genera without heterocysts is suggestive of a more general role.

Vertical distribution and migration of planktonic rotifers in Xiangxi Bay of the three Gorges Reservoir, China

We investigated diel vertical migrations (DVM) and distributions of rotifers in summer, 2004 and spring, 2005, in Xiangxi Bay of the Three Gorges Reservoir, China. Water temperature, pH, conductivity, and phytoplankton were closely related to rotifer vertical distribution, while dissolved oxygen had no relationship with the vertical distribution of rotifers. The species composition and population density of rotifers changed significantly between seasons. However, rotifer vertical distributions in both seasons were similar. They aggregated at specific depths in the water column. All the rotifer species inhabited the surface layers (0.5-5 m). Generally, the rotifers did not display DVM except for Polyarthra vulgaris (in summer), which performed reverse migration. The reason that rotifers did not perform DVM may be explained by the low abundance of competitors and predators and the high density of food resources at the surface strata.

Performance and mechanism of phosphorus removal in an integrated vertical flow constructed wetland treating eutrophic lake water

Phosphorus removal performance and a possible mechanism for the phosphorus removal from an eutrophic lake water were investigated using a medium-scale integrated vertical constructed wetland (combined vertical and reverse-vertical systems) from April, 11, 2001 to September, 28, 2004. Environmental factors affecting phosphorus removal and release profiles were monitored simultaneously under hydraulic loads from 400 to 2000 mm per day. The phosphorus removal rate varied with the environmental conditions. The removal rate for acidic influent water was superior to that for alkaline influent water. The substrate in the wetland chamber acted as a buffer to regulate the pH value of the water sample. As regards the water temperature, no significant differences were observed for the removal rate of total phosphorus (TP) and soluble reactive phosphorus (SRP) between low (lower than 15 degrees C) medium (16-25 degrees C) and high temperature (higher than 26 degrees C) conditions. Under a hydraulic load of 400 mm per day, the removal rate reached over 70%, the highest value achieved in this work. In addition, the highest hydraulic load of 2000 mm/d did not result in the lowest removal rate, as had been expected. After a two-year high hydraulic load test, the removal rate decreased significantly. Phosphorous release from the substrate was examined using a spatial sampling method. Depth profiles of total phosphorus and different states of phosphorus present in the substrate were recorded. This further study demonstrated that binding of phosphorus by iron and calcium might be another major factor in the removal and release of TP and SRP in this wetland system. The distribution of the speciated phosphorus showed that the amount of phosphorus captured in the substrate of the down-flow chamber was significantly higher than that captured in the up-flow chamber, suggesting that the up-flow chamber was the main source of phosphorus release in this constructed wetland.

Vertical mixing within the epilimnion modulates UVR-induced photoinhibition in tropical freshwater phytoplankton from southern China

1. The importance of vertical mixing in modulating the impact of UVR on phytoplankton photosynthesis was assessed in a tropical, shallow lake in southern China from late winter to mid-spring of 2005. 2. Daily cycles of fluorescence measurements (i.e. photosynthetic quantum yield, Y) were performed on both 'static' and in situ samples. Static samples were of surface water incubated at the surface of the lake under three radiation treatments - PAB (PAR + UVR, 280-700 nm), PA (PAR + UV-A, 320-700 nm) and P (PAR, 400-700 nm). In situ samples were collected every hour at three different depths - 0, 0.5 and 1 m. 3. The general daily pattern was of a significant decrease in Y from early morning towards noon, with partial recovery in the afternoon. Samples incubated under static conditions always had lower Y than those under in situ conditions at the same time of the day. 4. Under stratified conditions, no overall impact of UVR impact could be detected in situ when compared with the static samples. Further rapid vertical mixing not only counteracted the impact of UVR but also stimulated photosynthetic efficiency. 5. Based on these measurements of fluorescence, the mixing speed of cells moving within the epilimnion was estimated to range between 0.53 and 6.5 cm min(-1). 6. These data show that mixing is very important in modulating the photosynthetic response of phytoplankton exposed to natural radiation and, hence, strongly conditions the overall impact of UVR on aquatic ecosystems.

Population genetic structure of Carchesium polypinum (Ciliophora : Peritrichia) in four chinese lakes inferred from ISSR fingerprinting: High diversity but low differentiation

Although the peritrichous ciliate Carchesium polypinum is common in freshwater, its population genetic structure is largely unknown. We used inter-simple sequence repeat (ISSR) fingerprinting to analyze the genetic structure of 48 different isolates of the species from four lakes in Wuhan, central China. Using eight polymorphic primers, 81 discernible DNA fragments were detected, among which 76 (93.83%) were polymorphic, indicating high genetic diversity at the isolate level. Further, Nei's gene diversity (h) and Shannon's Information index (I) between the different isolates both revealed a remarkable genetic diversity, higher than previously indicated by their morphology. At the same time, substantial gene flow was found. So the main factors responsible for the high level of diversity within populations are probably due to conjugation (sexual reproduction) and wide distribution of swarmers. Analysis of molecular variance (AMOVA) showed that there was low genetic differentiation among the four populations probably due to common ancestry and flooding events. The cluster analysis and principal component analysis (PCA) suggested that genotypes isolated from the same lake displayed a higher genetic similarity than those from different lakes. Both analyses separated C. polypinum isolates into subgroups according to the geographical locations. However, there is only a weak positive correlation between the genetic distance and geographical distance, suggesting a minor effect of geographical distance on the distribution of genetic diversity between populations of C. polypinum at the local level. In conclusion, our studies clearly demonstrated that a single morphospecies may harbor high levels of genetic diversity, and that the degree of resolution offered by morphology as a marker for measuring distribution patterns of genetically distinct entities is too low.