梨头霉11α—羟基化制备16β—甲基—11α,17α21—三烃基孕甾—1, …

选育到一株对１６β－甲基－１７α,２１－二羟基孕甾－１,４＝－二烯－３,２０－二酮（Ⅱａ）１１α－羟基化活性强的梨头霉Ａ２８菌株,并发现底物２１－乙酰化（Ⅱｂ）可明显提高１１α－羟工 能力。在适宜的转化条件下,１１ｂ投料浓度０．５％,产物１６β－基１１α,１７α,２１－三羟基孕甾－１,４－二烯－３,２０－二酮（Ⅲ）收率为７３％,结构经波谱分析确认。     

Genetic structure of Balearic honeybee populations based on microsatellite polymorphism

The genetic variation of honeybee colonies collected in 22 localities on the Balearic Islands (Spain) was analysed using eight polymorphic microsatellite loci. Previous studies have demonstrated that these colonies belong either to the African or west European evolutionary lineages. These populations display low variability estimated from both the number of alleles and heterozygosity values, as expected for the honeybee island populations. Although genetic differentiation within the islands is low, significant heterozygote deficiency is present, indicating a subpopulation genetic structure. According to the genetic differentiation test, the honeybee populations of the Balearic Islands cluster into two groups: Gimnesias (Mallorca and Menorca) and Pitiusas (Ibiza and Formentera), which agrees with the biogeography postulated for this archipelago. The phylogenetic analysis suggests an Iberian origin of the Balearic honeybees, thus confirming the postulated evolutionary scenario for Apis mellifera in the Mediterranean basin. The microsatellite data from Formentera, Ibiza and Menorca show that ancestral populations are threatened by queen importations, indicating that adequate conservation measures should be developed for protecting Balearic bees.     

Relationship between oviposition preference and offspring performance in Australian Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract We investigated the oviposition preference and larval performance of Helicoverpa armigera under laboratory conditions to determine if the oviposition preference of individual females on maize, cowpea and cotton correlates with offspring performance on the leaves of the same host plants. The host-plant preference hierarchy of females did not correlate with their offspring performance. Female moths chose host plants that contributed less to their offspring fitness. Plant effects accounted for the largest amount of variation in offspring performance, while the effects of female (family) was low. The offspring of most females (80%, n  = 10) were broadly similar, but 20% (two out of 10), showed marked difference in their offspring performance across the host-plant species. Similarly, there was no relation between larval feeding preference and performance. However, like most laboratory experiments, our experi-mental design does not allow the evaluation of ecological factors (for example, natural enemies, host abundance, etc.) that can play an important role in larval performance in the field. Overall, the results highlight the importance of carrying out preference performance analysis on the individual or family level, rather than pooling individuals to obtain average population data.     

Nitrogen and phosphorus removal by wetland mesocosms subjected to different hydroperiods

The effect of hydroperiod on nutrient removal efficiency from simulated wastewater was investigated in replicate wetland mesocosms (area, 2 m², planted with Scirpus californicus). Alternate draining and flooding of sediments (pulsed discharge) increased nutrient removal efficiency compared to the continuous-flow “control”. Average PO₄³⁻ removal efficiency was 20–30% higher in wetland mesocosms that drained twice daily compared to the control. Inorganic N removal efficiency was less affected than phosphate removal by hydroperiod variation. At the higher NH₄⁺ loading rate (1.83 g N m⁻² day⁻¹), inorganic N removal efficiency was consistently 5–20% higher in pulsed-discharge wetland mesocosms than in the control. At the lower NH₄⁺ loading rate (0.9 g N m ⁻² day ⁻¹), pulsed-discharge hydrology had no effect on inorganic N removal efficiency. Twice-daily drainage exhibited average inorganic N removal efficiencies of 96% (lower N loading rate) and 87% (higher N loading) and average phosphate removal efficiencies of 81% (lower P loading) and 90% (higher P loading). Mass balance data from the continuous-flow treatment revealed that the aquatic macrophyte Scirpus californicus was the most important nutrient sink, assimilating 50% of the NH₄⁺ and PO₄³⁻ supply. The high plant productivity in the mesocosms (15.6 kg m⁻² year⁻¹) occurred under conditions of high light (high edge per mesocosm area) and high root contact with nutrient-rich influent (shallow, sandy substrate) and may overestimate plant uptake in larger wetlands. The addition of a nitrification-inhibitor (N-Serve) indicated that 34% of the NH₄⁺ supply was transformed to NO₃⁻ by nitrifying bacteria.     

新生隐球菌嗜中枢性感染机制的研究进展

新生隐球菌是临床上最重要的侵袭性病原真菌之一,可感染免疫抑制和免疫正常人群引发具有致命威胁的隐球菌性脑膜脑炎.近年来,隐球菌嗜中枢神经系统感染的机制研究取得了长足的进展,隐球菌参与侵袭中枢神经系统的相关毒力因子及多条宿主细胞应答信号通路相继被发现.     

Pleistocene climate change promoted rapid diversification of aquatic invertebrates in Southeast Australia

ABSTRACT: BACKGROUND: The Pleistocene Ice Ages were the most recent geohistorical event of major global impact, but their consequences for most parts of the Southern hemisphere remain poorly known. We investigate a radiation of ten species of Sternopriscus, the most species-rich genus of epigean Australian diving beetles. These species are distinct based on genital morphology but cannot be distinguished readily by mtDNA and nDNA because of genotype sharing caused by incomplete lineage sorting. Their genetic similarity suggests a Pleistocene origin. RESULTS: We use a dataset of 3858 bp of mitochondrial and nuclear DNA to reconstruct a phylogeny of Sternopriscus using gene and species trees. Diversification analyses support the finding of a recent rapid speciation event with estimated speciation rates of up to 2.40 species per MY, which is considerably higher than the proposed average rate of 0.16 species per MY for insects. Additionally, we use ecological niche modeling and analyze data on habitat preferences to test for niche divergence between species of the recent Sternopriscus radiation. These analyses show that the species can be characterized by a set of ecological variables referring to habitat, climate and altitude. CONCLUSIONS: Our results suggest that the repeated isolation of populations in glacial refugia might have led to divergent ecological adaptations and the fixation of morphological traits supporting reproductive isolation and therefore may have promoted speciation. The recent Sternopriscus radiation fulfills many characteristics of a species flock and would be the first described example of an aquatic insect species flock. We argue that the species of this group may represent a stage in speciation past the species flock condition because of their mostly broad and often non-overlapping ranges and preferences for different habitat types.     

Induction of multidrug resistance proteins MRP1 and MRP3 and gamma-glutamylcysteine synthetase gene expression by nonsteroidal anti-inflammatory drugs in human colon cancer cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been demonstrated to suppress colorectal tumorigenesis. NSAIDs have also been used to treat inflammatory illnesses. However, the underlying mechanisms of action by NSAIDs have not been completely elucidated. In this study, we reported that among the six members of the multidrug resistance protein gene (MRP1 to MRP6) family which encode membrane transporters for a diverse group of antitumor agents, expression of MRP1 and MRP3 but not the others in human colorectal cancer cell lines was induced by sulindac. This induction profile is consistent with the results using prooxidants which produce reactive oxygen species (ROS) and generate oxidative stress as previously reported. Moreover, treatment of colorectal cancer cells with sulindac induced ROS. Suppression of ROS formation by antioxidant N-acetylcysteine (NAC) downregulated the induction of MRP1 and MRP3 expression. Expression of another oxidative stress-sensitive gene, gamma-glutamylcysteine synthetase heavy subunit gene (gamma-GCSh), which encodes the rate-limiting enzyme in glutathione biosynthesis, was also induced by sulindac. However, the suppression of sulindac-induced gamma-GCSh expression by NAC was less sensitive compared with that of MRP1 and MRP3. We also demonstrated that induction of MRP3 and gamma-GCSh was independent of intracellular COX-2 levels. These results, collectively, suggest a ROS-related, COX-2-independent mechanism for the induction of drug resistance gene expression that bears important implications to the roles of NSAIDs in colorectal carcinogenesis and inflammatory response.     

敦煌西湖湿地鸟类栖息地重要性模糊综合评判

根据2007～2008年在甘肃敦煌西湖国家级自然保护区进行的湿地鸟类调查种类和数量数据,运用模糊综合评判法对保护区内的8块湿地进行了湿地鸟类栖息地重要性评价. 评判中隶属度的确定采用最佳因子值法,并分春、秋两种最佳因子值进行评判.结果表明:(1)春季各湿地均比秋季的重要性程度高,春季是管理的重点;(2)春秋两季南湖湿地重要性(0.938和0.966)都要远大于其它的湿地.春季盐池湾、羊水海子、南大湖的结果较相近,重要性程度次之,可持有相同程度的管理水平.党河水库、墩子湾、马圈湾、南园湖的重要性程度较低,只需一般水平的管理;(3)秋季各湿地水平除了南湖外普遍较低,羊水海子和盐池湾的重要性(0.340和0.269)相对较高些,但也只需一般水平的管理.