Degradation of three herbicides, atrazine, cyanazine and dicamba, was assessed in laboratory microcosms incubated under simulated methanogenic conditions using sediment from Pearl River of Southern China as an inoculum. Atrazine was much more resistant to degradation than cyanazine and dicamba over 300 days of incubation. Biodegradation of cyanazine and dicamba was further substantiated by establishment of enrichment transfer cultures in which the degradation of the respective herbicide was accelerated by the active microorganisms. Degradation of cyanazine initially involved the removal of chlorine and the two side chains, while that of dicamba was O-demethylation reaction forming 3, 6-dichlorosalicyclic acid. Results suggest that biodegradation of xenobiotics can be established through enrichment culture transfer technique, and further mechanism of degradation and microorganisms involved can be elucidated.

The perennial chenopod sub-shrub Artemisia halodendron Turcz. ex Bess. is endemic to the semi-xed and mobile sand dunes in Inner Mongolia of northern China and is an important sand-stabilizing plant. A. halodendron can persist through either sexual reproduction (seed- ling recruitment) or vegetative propagation. However, it is not known if there are differences in patterns of reproductive allocation in A. halodendron inhabiting semi-xed and mobile habitats. To characterize this, a test of eld measurements was conducted on two typical semi-xed and mobile sand dune habitats. In each habitat, 120 individual A. halodendron plants were randomly sampled at the time of seed production to examine changes in some reproductive characters including the number of owering shoots, dry weight of owering shoots, dry weight per owering shoot, dry weight of seed, and reproductive effort (RE = seed dry weight/total above-ground dry weight) between habitats. Although total above-ground dry weight and dry weight of vegetative biomass were similar between habitats, plants inhabiting the less eroded semi-xed habitat produced more owering shoots, greater dry weight of owering shoots, dry weight of seed and RE than those inhabiting the more eroded mobile habitat. This suggests that sexual reproduction is relatively favored by plants from the semi-xed habitat, whereas vegetative propagation is favored by plants from the mobile habitat. The allocation of resources to reproduction was size-dependent and specic to habitats sampled. Reproductive biomass and the number of owering shoots per plant increased with increasing vegetative biomass, with plants in the semi-xed habitat producing more owering shoots and greater reproductive biomass than plants in the mobile habitat. Plant size did not inuence RE, indicating that allocation of resources to reproduction appeared to be a constant proportion across all plant sizes sampled.

The single-chain insulin (PIP) can spontaneously fold into native structure through preferred kinetic inter-mediates. During refolding, pairing of the first disulfide A20–B19 is highly specific, whereas pairing of the second disulfide is likely random because two two-disulfide intermediates have been trapped. To get more details of pairing property of the second disulfide, four model peptides of possible folding intermediates with two disulfides were prepared by protein engineering, and their properties were analyzed. The four model peptides were named [A20–B19, A7–B7]PIP, [A20–B19, A6–B7]PIP, [A20–B19, A6–A11]PIP, and [A20– B19, A7–A11]PIP according to their remaining disulfides. The four model peptides all adopt partially folded structure with moderate conformational differences. In redox buffer, the disulfides of the model peptides are more easily reduced than those of the wild-type PIP. During in vitro refolding, the reduced model peptides share similar relative folding rates but different folding yields: The refolding efficiency of the reduced [A20–B19, A7–A11]PIP is about threefold lower than that of the other three peptides. The present results indicate that the folding intermediates corresponding to the present model peptides all adopt partially folded conformation, and can be formed during PIP refolding, but the chance of forming the intermediate with disulfide [A20–B19, A7–A11] is much lower than that of forming the other three intermediates.

The zooplankton of 18 reservoirs of South China was investigated in 2000. 61 Rotifera species, 23 Cladoceras and 14 Copepodas were identified. The most frequent Rotifera genera were Keratella, Brachionus, Trichocerca, Diurella, Ascomorpha, Polyarthra, Ploesoma, Asplanchna, Pompholyx and Conochilus. Bosmina longirostris, Bosminopsis deitersi, Diaphanosoma birgei, D. brachyurum and Moina micrura were typical of Cladocera in the reservoirs. Phyllodiaptomus tunguidus, Neodiaptomus schmackeri and Mesocyclops leuckarti were the most frequent Copepoda and M. leuckarti dominated Copepoda in most reservoirs. High zooplankton species richness with low abundance was characteristic of the throughflowing reservoir, whereas low species richness with low abundance was found in the reservoir with the longest retention time. Relative high abundance and medium species diversity were the distinction of intermediate retention time reservoirs.

以绿色巴夫藻（Pavlova viridis）为实验材料,设置了18、36、54、65、86和108J．m-2 6个UV-B辐射剂量处理组,以无紫外辐射为对照,解除胁迫后,处理组和对照组在相同接种密度和相同条件下培养12d,测定了生长过程中的吸光值、生物量、叶绿素a、类胡萝素、可溶性蛋白质和胞内多糖含量,结果表明,在UV-B胁迫下,绿色巴夫藻细胞生长受到显著抑制,6个处理组细胞的相对增长率比对照下降了16.15%-60.00%(P<0.05)．但在胁迫解除后,各胁迫处理的藻细胞生长指标均显著高于对照(P<0.05),证明绿色巴夫藻在胁迫后的恢复生长中出现超补偿生长现象,恢复培养第12天,最大吸光值、生物量、叶绿素a、类胡萝素、可溶性蛋白质和胞内多糖含量分别比对照提高了22. 38%、15.00%、26.15%、23.81%、11.63%和27.58%．藻类中存在超补偿生长特性为微藻生物活性物质的开发提供了有效途径,