超强静磁场对染料脱色菌Escheriehia coli的acpD基因的影响

将大肠杆菌E.coli ATCC8739置于12.0 T超强静磁场(ultra-strong static magnetic field,SMF)中进行处理,获得了磁场处理0.5、1、2、4和8 h的菌株E.coli-SMFn(n=0.5、1、2、4、8)。在37℃、pH 7、静置的条件下,菌株对偶氮染料AR14(I.C.Acid Red 14)的脱色结果指出,当反应进行到4、6和8 h时,E.coli-SMF8的脱色效率分别为18%、55%和96%,远高于E.coli ATCC8739的3%、19%和50%,表明SMF作用显著地增强了菌株的脱色效率。基因组DNA提取、PCR扩增、分子克隆以及基因测序的实验结果进一步表明,全部6例E.coli ATCC8739菌株的偶氮还原酶基因(acpD)序列均与GenBank中报道的完全一致;而E.coli-SMF8菌株的acpD-SMF8核酸序列中缺失了第99位的胞嘧啶。该缺失突变不仅使acpD-SMF8的核酸序列与acpD的存在显著不同,同时得到了具新活性中心的偶氮还原酶AzoR-SMF8。这个新的活性中心具有更强的黄素(FMN)结合能力,因此使该酶与偶氮染料的亲和力大大增加,促进了脱色效率的提高。     

Changes in TcpA gene frequency explain 2,4,6-trichlorophenol degradation in mesocosms

Soils are often polluted by chlorophenols in timber production areas in the northern hemisphere. The tcpA gene encodes the first step of 2,4,6-trichlorophenol (246-TCP) degradation. We tested tcpA gene frequency in three natural pristine soils with different 246-TCP degradation capacity. Gene tcpA frequency increased more in spiked than non-spiked 10-L pails containing coniferous humus soil with high degradation capacity, in contrast to soils where degradation was slower. As the soil in each mesocosm originated from a spatially separate field plot, changes in tcpA gene frequency affected 246-TCP degradation over a range of soil origins. This indicates that the abundance of and changes in tcpA gene frequency could be utilized in estimating the efficacy of natural attenuation and biostimulation treatments in controlled conditions.     

Salmonella Enterica Serovar Typhimurium HilA-LacZY Fusion Gene Response to Iron Chelation or Supplementation in Rich and Minimal Media

Abstract

Virulence expression of Salmonella enterica serovar Typhimurium under iron limited condition was measured by β-galactosidase (β-gal) assay using a hilA-lacZY fusion strain and calculated as Miller units. hilA-lacZY β-galactosidase assays were performed in brain heart infusion (BHI) and minimal media (M9), after iron chelation with 2, 2-dipridyl and iron-supplementation respectively. Before performing virulence assays, concentrations of iron in the media were estimated using ferrozine. Iron content was found to be more in BHI (42.6 µg dL^?1) as compared to M9 (10.03 µg dL^?1). β-gal activity of Salmonella Typhimurium in BHI was generally less than that observed in M9. After exposure to various combinations of iron chelator in BHI, hilA-lacZY activity only increased at the highest concentration of chelator (200 µM) but decreased in M9 media for all iron concentrations when compared to controls with no iron amendment. These results indicate that iron availability may influence S. Typhimurium hilA expression.     

高效降解环己酮红球菌JDM-3-12的分离及其系统发育分析

从岳阳巴陵石化公司环己酮生产车间总出水口的污泥中筛选到一株环己酮降解菌株,菌号为JDM-3-12;该菌能以环己酮为唯一碳源且能忍受5000 mg/L的环己酮,当环己酮的质量浓度为2000 mg/L时,在温度为30℃,转速为150 r/m in,pH=7的条件下,72小时内该菌株对环己酮的降解率达到97.91%。通过形态观察、生理生化特征检测和基于16S rRNA基因序列的系统发育分析,初步鉴定其为赤红球菌(Rhodococcus ruber)中的一个菌株,该菌最适生长温度为35℃,最适生长pH 7。     

家蚕斑纹限性品种SC_1的RAPD差异DNA片段的克隆及其酶切图谱分析

利用RAPD技术对家蚕限性普斑品种SC1的雌雄体分别进行PCR扩增通过120种引物的筛选,得到1个雌体特异的RAPDDNA片段将该片段克隆到pUC19质粒,井进行了限制性内切酶图谱分析.     

Xα21基因导入水稻及转基因植株的鉴定

以水稻愈伤组织为受体、质粒pCXK1301为Xα21基因供体,用农杆菌EHA105和PDS－1000／He基因枪转化受体,经Hyg浓度梯度筛选,获得一些转基因水稻植株,GUS检测、PCR扩增和Southern杂交分析表明,报告基因（GUS）、选择标记基因（Hyg^r）和抗白叶枯病基因Xα21都已整合入转化水稻基因组中,Southern杂分析显示了Xα21基因在转化水稻基因组中整合的拷贝数。田间接菌鉴定表现抗白叶枯病。     

Ants as a Measure of Effectiveness of Habitat Conservation Planning in Southern California

Abstract: In the United States multispecies habitat conservation plans were meant to be the solution to conflicts between economic development and protection of biological diversity. Although now widely applied, questions exist concerning the scientific credibility of the conservation planning process and effectiveness of the plans. We used ants to assess performance of one of the first regional conservation plans developed in the United States, the Orange County Central‐Coastal Natural Community Conservation Plan (NCCP), in meeting its broader conservation objectives of biodiversity and ecosystem‐level protection. We collected pitfall data on ants for over 3 years on 172 sites established across a network of conservation lands in coastal southern California. Although recovered native ant diversity for the study area was high, site‐occupancy models indicated the invasive and ecologically disruptive Argentine ant (Linepithema humile) was present at 29% of sites, and sites located within 200 m of urban and agricultural areas were more likely to have been invaded. Within invaded sites, native ants were largely displaced, and their median species richness declined by more than 60% compared with uninvaded sites. At the time of planning, 24% of the 15,133‐ha reserve system established by Orange County NCCP fell within 200 m of an urban or agricultural edge. With complete build out of lands surrounding the reserve, the proportion of the reserve system vulnerable to invasion will grow to 44%. Our data indicate that simply protecting designated areas from development is not enough. If habitat conservation plans are to fulfill their conservation promise of ecosystem‐level protection, a more‐integrated and systematic approach to the process of habitat conservation planning is needed.     

Genetic Bottlenecks Driven by Population Disconnection

Abstract: Connectivity among populations plays a crucial role in maintaining genetic variation at a local scale, especially in small populations affected strongly by genetic drift. The negative consequences of population disconnection on allelic richness and gene diversity (heterozygosity) are well recognized and empirically established. It is not well recognized, however, that a sudden drop in local effective population size induced by such disconnection produces a temporary disequilibrium in allelic frequency distributions that is akin to the genetic signature of a demographic bottleneck. To document this effect, we used individual‐based simulations and empirical data on allelic richness and gene diversity in six pairs of isolated versus well‐connected (core) populations of European tree frogs. In our simulations, population disconnection depressed allelic richness more than heterozygosity and thus resulted in a temporary excess in gene diversity relative to mutation drift equilibrium (i.e., signature of a genetic bottleneck). We observed a similar excess in gene diversity in isolated populations of tree frogs. Our results show that population disconnection can create a genetic bottleneck in the absence of demographic collapse.     

Management plan for an alkali sink and its endangered plantCordylanthus palmatus

Cordylanthus palmatus is a hemiparasitic annual of the family Scrophulareacae. It is on both the federal and state lists of endangered species. Only four widely separated populations remain, all of them in alkali sinks, where the plant thrives in saline-sodic soils. The largest population is at Springtown, Alameda County, California. This article reports on efforts to develop a management plan for both the plant and the alkali sink ecosystem. The plan is based on: (1) characterization of hydrology, soils and geomorphology of the site; (2) characterization of the land use impacts to the site; (3) analysis of plant distribution in relation to gradients of elevation and soil chemistry; (4) studies on water potential and water stress inCordylanthus palmatus and associated species. On the basis of this plan, both the State of California and private groups are cooperating to create, restore, and manage a preserve in the Springtown Alkali Sink.